DESIGN, BUILD AND OPERATION OF THE NHIEU LOC THI NGHE
WASTEWATER TREATMENT PLANT, HO CHI MINH CITY (NLTN
WWTP)
Leader
REPORT
GENERAL MECHANICAL DESIGN CRITERIA
A V J - A






Comments:
Reviewed/
Approved
by:
0
0
0 - M E - R P T - 1
0
0
1 - A
EMPLOYER’S APPROVAL
Code 0: Recommended for approval by EPMR
Code 1: Approved by EPM
Code 2: Approved with comments
Code 3: Amend and resubmit
Code 4: Rejected
Code 5: For information only
(Name, Signature, Date and Stamp)
A
2020-07-31
PS
JBL
SBG
Technical Design First Issue
Rev.
Date
Preparation
Review
Approval
Changes/Comments
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
2 / 32
TABLE OF CONTENTS
1
SCOPE
5
2
DOCUMENTS OF REFERENCE
5
3
DESIGN
5
3.1 UNITS
5
3.2 STANDARD AND CODES
6
3.3 INTERNATIONAL STANDARDS
3.3.1
MECHANICAL
3.3.2
PIPEWORK
7
7
7
3.4 GEOGRAPHICAL LOCATION
8
3.5 ENVIRONMENTAL CONDITIONS
3.5.1
GENERAL CLIMATE
3.5.2
TEMPERATURE, RAINFALL AND HUMIDITY
3.5.3
SEISMOLOGICAL DATA
8
8
8
10
3.6 GENERAL MATERIAL REQUIREMENTS
10
3.7 WARRANTY
10
3.8 DESIGN PRESSURE
10
3.9 DESIGN TEMPERATURE
11
3.10 DESIGN LIFE
11
4
11
METALIC WELDING
4.1 GENERAL
11
4.2 STANDARDS
11
4.3 WELDER QUALIFICATIONS
11
4.4 WELDING INSPECTION AND TESTING
11
4.5 PROTECTIVE COATINGS
12
5
12
MECANICAL EQUIPMENT
5.1 DESIGN
12
5.2 VESSELS
5.2.1
PRESSURE VESSELS
5.2.2
TANKS
13
13
13
5.3 ACCESS
13
5.4 ALUMINIUM PLATES AND SECTIONS
13
5.5 STAINLESS STEEL
13
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
3 / 32
5.6 FABRICATION
5.6.1
METAL WORK
5.6.2
STORAGE
14
14
14
6
PIPING
14
6.1 LINE SIZING
14
6.2 ALLOWABLE PRESSURE DROP
14
6.3 PIPING MATERIALS
6.3.1
METALLIC PIPING
6.3.2
NON-METALLIC PIPING
15
15
15
6.4 SAFETY SHOWER AND EYEWASH
16
6.5 PIPING SUPPORTS
6.5.1
SPECIAL PIPE SUPPORTS
16
16
7
16
STRUCTURAL DESIGN FOR EQUIPMENT
7.1 GENERAL
16
7.2 LOADS
7.2.1
7.2.2
7.2.3
PERMANENT LOADS (W)
VARIABLE LOADS (W)
EARTHQUAKE LOADS (E)
17
17
17
17
8
PROVISIÓN FOR HANDLING EQUIPMENT
17
9
SPECIAL TOOLS
17
10
NOISE AND VIBRATION
17
10.1 SOUND PRESSURE LEVEL
17
10.2 NOISE SURVEY
18
10.3 NOISE CONTROL
18
10.4 THERMAL AND ACOUSTIC INSULATION
10.4.1
GENERAL
10.4.2
INSULATION OF INDIVIDUAL ITEMS
10.4.3
VIBRATION
18
18
18
19
11
LUBRICATION
19
11.1 FIRST FILL & FLUSH
19
11.2 RECOMMENDATION BY SUPPLIER
19
11.3 GREASE LUBRICATION POINTS
19
12
19
PROTECTION OF METAL WORK FROM CORROSION
12.1 GENERAL
19
12.2 SURFACE PREPARATION AND CLEANING OF SURFACES IN THE SHOP
20
12.3 CLEANING OF PRIME AND INTERMEDIATE COATS (IF REQUIRED)
20
12.4 APPLICATION PROCEDURE
20
12.5 GALVANIZING
21
12.6 COATING SYSTEM
22
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
4 / 32
12.7 DESIGN CORROSION CONTROL & DURABILITY
23
13
PRE-SERVICE CLEANING AND PROTECTION OF SYSTEM EQUIPMENT
26
14
SAFETY
26
14.1 PROTECTION OF PERSONNEL
26
14.2 SAFETY OF MACHINERY
26
14.3 INTERLOCKS
26
14.4 INSPECTION OPENINGS
26
14.5 COUPLING GUARDS
27
15
27
FASTENERS
15.1 MECHANICAL FASTENERS
15.1.1
MATERIALS
27
27
15.2 PASSIVATION OF STAINLESS STEEL FASTENERS
27
16
ERECTION MARKS
27
17
LABELS
28
18
PIPELINE IDENTIFICATION
28
19
NAMEPLATES
28
20
INSPECTION AND TESTING
31
20.1 SCOPE
31
20.2 STAGES OF TESTING
31
20.3 INSPECTION POINTS PROGRAM (IPP)
31
20.4 GENERAL REQUIREMENTS FOR TESTING
31
20.5 FACTORY ACCEPTANCE TESTION AND INSPECTION
20.5.1
TEST PLAN AND PROCEDURE
20.5.2
FAT AND INSPECTION REPORT
31
31
32
21
32
PRE-COMMISSIONING
21.1 PRE-COMMISSIONING INSPECTIONS AND TESTS
32
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
1
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
5 / 32
SCOPE
The aim of this report is to establish the design criteria for all mechanical and chemical equipment, piping and
associated items, which form part of THE NHIEU LOC THI NGHE WASTEWATER TREATMENT PLANT, HO
CHI MINH CITY (NLTN WWTP).
The different equipment that are affected by this design criteria are: pumps, valves, penstocks, mixers, tanks,
chemical equipment, pipes, silos, and any other process related equipment.
The specific requirements of the equipment, valves, material and other individual specifications and data sheets have
precedence over the requirements of this General Mechanical Design Criteria.
This design criteria does not apply to Building Services, firefighting or HVAC equipment. This design criteria does
also not apply to civil structures and access platforms.
2
DOCUMENTS OF REFERENCE
The design shall consider the different documents included by the client as Tender Documents:
Title
Volume 2 Part 2 – Employer’s Requirements
XL-02 Response to the Request of Clarification of Bidders
XL-02 Amendments to Bidders
3
DESIGN
Mechanical materials and equipment will comply with the technical codes of the International Organization for
Standardization (ISO), European codes EN, EN-BS, EN-DIN; American codes ANSI, ASME, ASTM, AWWA,
IEEE, API and/or Vietnam code TCVN. The specification and data sheets will reflect the specific standards in each
case.
If any Vietnamese regulation is contradicting to any standard given in this design criteria, it is the obligation of the
Contractor to apply the Code with the highest requirement of quality, functionality and appropriateness.
Application of standards shall be consistent for the equipment. In addition, standardisation of equipment
(mechanical and electrical) across the Plant is desirable, and compatibility of equipment across the plant is essential.
Generally, all internationally recognized Norms and Standards are accepted. Nevertheless, with respect to safety,
health and working protection the related standards and laws which are directly linked to local legal provisions, the
local law respectively the relevant binding local standards and norms shall be applied.
3.1 UNITS
All units shall be expressed in SI (International System of Units).
All piping sizes shall be expressed by nominal sizes: DN (diameter nominal) – mm (inches occasionally).
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Parameter
Weight
Volume
Length
Temperature
Pressure
Differential Pressure
Mass flow (general)
Water / volumetric flow:
- large quantities
- small quantities
Power
Energy Consumption
Mass
Force
Time
Velocity
Quantity
Rev.
A
Date
2020-07-31
Page
6 / 32
Units
kg,
metric ton (t)
cubic metre (m³),
litre (l)
m,
km
Degrees Celsius (°C)
absolute - Bar(a),
gauge - Bar(g),
mbar,
Pa
bar, mbar
kg/s, kg/h, t/h
m3/s or m3/h
l/min
MW
kW
Watt
Meg-volt-amp - MVA
kWh
kg, g; mg
N; kN
Hour (hr)
Minute (min)
Second (sec)
m/s
Milligram per litre - mg/l,
Parts per million - ppm,
3.2 STANDARD AND CODES
All materials and equipment supplied and all work carried out as well as calculation sheets, drawings, quality and
class of goods, methods of inspection, specific design features of equipment and parts and acceptances of partial
plants shall comply in every respect with the technical codes of the International Organization for Standardization
(ISO) and of the International Electro Technical Commission (IEC).
Goods and special guarantees beyond the scope of ISO or IEC shall conform at least to one of the following
standards and codes:
European
American
German
Japan
Vietnam
Pipes and accessories
VN01C2-ME-RP-1001
EN, EN-BS, EN-DIN
ANSI, ASME, ASTM, IEE, NEMA, NFPA,
AWWA, IEEE, API, NACE,TEMA
VDE, VDEW, DIN
Japanese Industrial Standard (JIS)
TCVN
shall be in accordance with British or American or
Japan or European standards if the use of other
standards is not specially requested.
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
7 / 32
Other internationally accepted standards which ensure a quality equal to or higher than the standards mentioned
above, but only if these are submitted in the English language (it is the obligation of Manufacturer/Contractor to
demonstrate this requirement).
3.3 INTERNATIONAL STANDARDS
The following list of international codes and standards when applicable shall apply. Where an international code of
higher standing exists to another similar international code, then the higher standing code shall take precedence.
3.3.1 MECHANICAL
EN ISO 9906
ISO 10816-1
BS EN 2516
ISO 3506
ISO 5752
ISO/TR 16880:
API std 670
ASME Section VIII,
Division 1
PED (97/23/EC)
API RP 2000
DIN 2532
ISO 4872
Roto-dynamic Pumps, Hydraulic Acceptance Tests
Mechanical Vibration. Evaluation of machine Vibration
Passivation of Corrosion Resisting Steels and Decontamination of Nickel Base Alloys
Mechanical properties of corrosion-resistant stainless steel fasteners
Metal valves for use in flanged pipe systems -- Face-to-face and centre-to-face dimensions
Cranes — Bridge and gantry cranes — International Standards for design and manufacturing
requirements and recommendations
Machinery protection systems
Design & Fabrication with Inspections, Repairs, and Alterations of Pressure Vessels
European Pressure Equipment regulation (97/23/EC)
Venting Atmospheric and Low-Pressure Storage Tanks
Cast Iron Flanges; Nominal Pressure 10
Acoustics – Measurement of airborne noise emitted by construction equipment intended for outdoor
use – Method for determining compliance with noise limits
3.3.2 PIPEWORK
TCVN 9113
TCVN 8492
TCVN 9070
ISO 7005-1
ISO 7005-2
ISO 1127
Reinforced concrete pipes for water draining
Spiral winding pipes of unplasticized poly (vinyl chloride) for non-pressure underground drainage
and sewerage systems
Corrugated pipe HDPE
Pipe flanges -- Part 1: Steel flanges for industrial and general service piping systems
Metallic flanges -- Part 2: Cast iron flanges
Stainless steel tubes. Dimensions, tolerances and conventional masses per unit length.
ISO 15493
Plastics Piping Systems for Industrial Applications – ABS, PVC-U and PVC-C – Specifications for
Components and the Systems – Metric Series
ISO 15494
Plastics Piping Systems for Industrial Applications – PB, PE and PP – Specifications for
Components and Systems – Metric Series
Plastics piping systems for water supply and for buried and above-ground drainage and sewerage
under pressure -Un-plasticized poly (vinyl chloride) (PVC-U)
Plastics piping systems -Polyethylene (PE) pipes and fittings for water supply
Ductile iron pipes, fittings, accessories and their joints for water applications
Cast Iron Flanges; Nominal Pressure 10
Face to face and end dimensions of valves
ISO 1452
ISO 4427
ISO 2531
DIN 2532
EN 558 part1, BS
5163.
EN10253-2
EN-1092
BS EN 1916
VN01C2-ME-RP-1001
Butt-welding pipe fittings - Part 2: Non alloy and ferritic alloy steels with specific inspection
requirements
Flanges and their joints. Circular flanges for pipes, valves, fittings and accessories, PN designated.
Steel flanges
Concrete pipes and fittings, unreinforced, steel fiber and reinforced
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
8 / 32
3.4 GEOGRAPHICAL LOCATION
The new Wastewater Treatment Plant (WWTP) shall be developed as a plant for wastewater inflow predominantly
of domestic origin and associated facilities, wherein the selected biological technology is MBBR.
Detailed design for the NLTN WWTP with a peak flow of 34,000 m³/h. Flows exceeding the max. allowed flow
shall be bypassed. Design pollution load is of 52,000 kg/BOD5/d and of 13,000 kg NH3-N/d.
Nhieu Loc Thi Nghe WWTP is located in Thanh My Loi Ward of District 2 / Ho Chi Minh City, Vietnam.
3.5 ENVIRONMENTAL CONDITIONS
Process and all the equipment provided shall be capable of satisfactory operation within the Vietnamese climate.
3.5.1 GENERAL CLIMATE
Vietnam's climate, being located in the tropics and strongly influenced by the South China Sea has a monsooninfluenced tropical climate typical of that of mainland Southeast Asia.
In the north, the climate is monsoonal with four distinct seasons (Spring, Summer, Autumn, and Winter) while in
the south (areas south of the Hải Vân Pass), the climate is tropical monsoon with two seasons (rainy and dry).
The area of Ho Chi Minh City has a tropical climate is a tropical savannah climate, with a two distinct seasons
(rainy and dry).
3.5.2 TEMPERATURE, RAINFALL AND HUMIDITY
According to QCVN 02:2009/BXD Vietnam Building code Natural Physical & Climatic Data for Construction and
Climatic Conditions in the Feasibility Study.
Unless otherwise specified the assembly and all the equipment provided shall be capable of satisfactory operation
within the temperature limits of -10°C to 50°C and relative humidity of 90 % comply with Vietnamese climate.
3.5.2.1. Temperature
The average air temperature is approximately 28.16ºC. The highest temperature is 34.2ºC (2000), the lowest
temperature is about 20.8ºC (2000). The average temperature over months from 2005 to 2010 as follows:
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
GENERAL MECHANICAL DESIGN
CRITERIA
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
Y\M
2005
2006
2007
2008
2009
I
26.2
27.2
27.3
27.2
25.9
Rev.
A
Date
2020-07-31
Page
9 / 32
II
III
IV
V
VI
VII
VIII
IX
X
XI
27.7
28.4
29.8
29.7
28.9
27.5
28.4
27.9
27.6
27.5
28.2
28.6
29.5
29.2
28.4
27.9
27.6
27.6
27.7
28.9
27.2
28.8
30.1
28.9
28.7
27.7
27.7
27.7
27.5
26.9
27.3
28.2
29.5
28.2
28.6
28.3
27.7
27.7
28.0
27.2
27.7
29.3
29.4
28.5
29.2
28.0
28.6
27.6
27.7
28.4
Source: Ho Chi Minh City Statistical Yearbook 2010, Tan Son Hoa Station
XII
262
27.3
27.6
26.9
27.5
Year
28.0
28.2
28.2
27.9
28.1
The table below reflects the average values of the last year weather conditions register.
Max. Ambient Air temperature
Min. Ambient Air temperature
Humidity
+40ºC
20ºC
50-90%
3.5.2.2. Sunshine hours
Total sunshine hours per year are 2,073.7 hours. Thereby, April is the month, which has the most hours of sunlight
(240.8 hours). The total of average daily radiation in a year is about 110-160 Kcal/cm2. The daylight hours in
months from 2005 to 2010 as follows:
Y\M
2005
2006
2007
2008
2009
I
II
III
IV
V
VI
VII
VIII
IX
X
XI
XII
164.8
131.0
113.3
156.3
174.4
215.3
157.7
193.6
135.6
168.1
252.9
221.6
229.5
216.7
236.9
225.6
213.4
213.5
188.3
186.7
200.4
208.7
182.5
165.7
155.9
185.6
161.5
128.0
172.8
191.6
153.1
140.2
147.7
218.7
149.2
178.1
157.2
135.8
161.0
155.7
142.2
141.4
130.8
142.6
116.9
138.8
127.2
147.0
152.4
132.3
124.6
142.1
127.5
145.4
147.7
90.5
121.2
141.8
134.1
187.6
Year
2,071.9
1,923.9
1,891.1
1,989.6
2,003.2
Source: Ho Chi Minh City Statistical Yearbook 2010, Tan Son Hoa Station
3.5.2.3. Rainfall
In the city area, the rainfall is uneven, tends to increase along the Southwest – North East. The suburban districts
and northern districts are higher rainfall than the rest of regions. Average annual rainfall of the city is high from
1,742.8 to 2,340.2 mm/year.
The rainfall concentrates on the rainy months, accounting for 90% of annual rainfall. Thereby, heavy rains usually
occur from August to October; especially, there is a little bit the amount of rainfall or no rainfall in January to
March. Monitoring data indicates that the average rainfall is 2,016.2 mm in 2010. The average rainfall (in mm)
monthly from 2005 to 2010 as follows:
Y\M
2005
2006
2007
2008
2009
I
0.4
9.5
0.3
II
III
IV
V
VI
VII
VIII
IX
X
XI
9.6
143.6 273.9 228.0 146.3 182.9 388.6 264.5
72.7
8.6
212.1 299.2 139.4 168.6 349.0 247.7 256.1 16.1
59.3
7.7
327.9 188.8 414.3 301.0 495.4 391.2 147.1
1.5
58.9 127.0 246.9 147.2 331.2 297.8 202.6 165.6 167.1
21.4 57.8 187.0 318.5 83.2 223.0 323.9 325.1 249.0 141.2
Source: Ho Chi Minh City Statistical Yearbook 2010, Tan Son Hoa Station
XII
105.4
28.9
7.1
57.8
49.5
Year
1,742.8
1,798.4
2,340.2
1,813.1
1,979.9
3.5.2.4. Humidity
The average humidity is 74%, the difference between the highest wet and dry place is about 10 to 12%. The highest
humidity in the rainy months is around 83% (September) and the lowest in the dry months is 68% (February). The
average humidity monthly from 2005 to 2010 as follows:
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
Y\M
2005
2006
2007
2008
2009
I
69
73
69
71
70
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
10 / 32
II
III
IV
V
VI
VII
VIII
IX
X
XI
69
67
70
74
77
81
78
80
82
79
68
71
73
75
81
81
82
81
81
75
68
71
69
80
80
83
82
83
82
76
69
71
73
81
78
79
83
83
81
79
73
71
76
81
77
79
80
83
80
73
Source: Ho Chi Minh City Statistical Yearbook 2010, Tan Son Hoa Station
XII
77
73
72
73
74
Year
75
76
76
77
76
3.5.3 SEISMOLOGICAL DATA
According to QCVN 02:2009/BXD Vietnam Building code Natural Physical & Climatic Data for Construction.
3.6 GENERAL MATERIAL REQUIREMENTS
The material selection shall take into account the generally aggressive environment within which the equipment
operates.
Regardless of whether a material of manufacture or minimum material requirement is specified, all material
selections shall be suitable and proven for use in the proposed application.
All materials shall be new and of the best quality for use in the conditions and the variations in temperature, pressure
and media that will be encountered in service without undue distortion or deterioration or the setting up of undue
strains in any part that might affect the efficiency and reliability of the plant.
All materials shall correspond either to the approved standards and the respective code number or to exact analysis
data, and full information concerning properties and applied heat, chemical and mechanical treatment shall be
submitted.
Special attention must be paid to eliminating the possibility of corrosion resulting from galvanic effects. Design,
selection of materials and all methods of erection shall be such as to keep these effects to a minimum.
All materials used shall be resistant to the media handled and to the environmental conditions. Consideration shall
also be given to conditions prevailing during transportation, storage and erection.
Amongst other things, following conditions and aspects shall be considered:






Corrosive environment with high ambient temperatures and high humidity;
Corrosive soil;
Corrosive and shallow ground water quality;
Solar radiation;
Design for the severe corrosion conditions; and
Consider ambient conditions as specified for the construction site;
3.7 WARRANTY
The equipment and installation shall be guaranteed for a period of at least one (1) year trouble free operation.
Effectively date of the warranty shall start on the same day the units have been accepted.
The supplier shall guarantee the availability of replacement parts and after sales service for a period of five (5) years
for each piece of equipment supplied.
3.8 DESIGN PRESSURE
Design pressure of the system shall never be less than the maximum pressure expected in service.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
11 / 32
3.9 DESIGN TEMPERATURE
Maximum design temperature shall not be less than the Maximum Operating Temperature expected in service.
Design margins shall be applicable according to ambient conditions and working requirements, as well as startup/shutdown conditions.
The design temperature shall be used to determine the design allowable stresses for the selected material in
accordance with the design code.
3.10 DESIGN LIFE
The work shall be designed for the following lifetime:
Mechanical Equipment shall be designed for long life and continuous 24 hour operation for prolonged periods with
a minimum of maintenance. The minimum design life shall be 15 years.
The requirements for design life shall govern the selection of materials.
4
METALIC WELDING
4.1 GENERAL
All welding, in general, shall be carried out to ISO standards or equivalent ASME.
The strength of all welded connections shall not be less than the strength of the parts being joined.
4.2 STANDARDS
The work shall be carried out in accordance with the relevant international standards.
4.3 WELDER QUALIFICATIONS
Skilled personnel appropriately qualified to relevant standards shall carry out welding. Alternatively, welders shall
be qualified by approved international equivalent standard. Copies of welder qualification certificates of the
personnel employed on the welding operations shall be provided.
All weld preparations, welding heat treatments, weld examination, welding equipment, filler wire, electrodes,
welding symbols, terms and definitions shall conform to international Standards. All welded components that
require machining and those where dimensional stability is important, shall be stress relieved. Where required, stress
relieving shall be carried out before final machining.
4.4 WELDING INSPECTION AND TESTING
All joints marked as potentially required for inspection, including welds, are to be left uninsulated, unpainted and
exposed for examination during testing.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
12 / 32
4.5 PROTECTIVE COATINGS
All equipment shall be coated in compliance with the working conditions to which it is exposed. For further details,
refer to section 12.
5
MECANICAL EQUIPMENT
5.1 DESIGN
The equipment to be supplied shall be new and clean, and it shall be manufactured and arranged under a functional
design and shall provide a pleasant appearance. All equipment of the WWTP shall be arranged in such a manner that
surveillance by the operator is easy, as well as maintenance, operation and control. The equipment to be provided
shall be state of the art supplied from well known manufacturers with high quality competitive standard.
The mechanical equipment shall be designed with operability, constructability, durability and safety considerations.
The equipment which is flanged shall conform to ISO 7005 PN10 or higher PN class if higher pressure is
functionally required.
The Contractor’s design shall show all required components of the WWTP and shall include complete process
dimensioning and hydraulic dimensioning and shall clearly indicate how to achieve environmental protection as
required by Vietnamese law and regulations.
The Equipment to be supplied shall be arranged so that they can be easily inspected, cleaned, erected and dismantled
without necessitating large scale dismantling of other parts of the Systems. The Equipment shall be manufactured,
mounted and put into operation in accordance with the latest recognized rules of workmanship, modern engineering
practice and with good standard of prudence applicable to the international standards and codes which would have
been expected to accomplish the desired result at the lowest reasonable cost consistent with reliability, safety and
expedition.
All applicable laws and governmental decrees, regulations, orders, the regulations as well as common international
standards and guidelines shall be observed in the design, calculation, manufacture, erection, installation, testing,
commissioning and start up of all parts of the Systems.
The following shall be considered in the engineering and construction of the facilities:
 All parts of the Systems shall be suitable in every respect for continuous operation at maximum load, as
well as part loads and expected transient operating conditions peculiar to the site and shall be able to safely
withstand the stresses arising from the operating conditions without any reduction in its planned life, which
shall be at least equal to the design life time defined.
 The Contractor shall familiarize himself with the conditions on site.
 Switchover to stand by units shall be automatic, as far as required for continuous operation of the systems.
 Minor equipment, which, in case of failure would cause a failure of a pumping station and/or the entire
System, is to be provided with a standby facility in order to ensure further operation of the facilities.
 All live, moving and rotating parts shall be provided with appropriate effective protection in order to avoid
danger to the operating staff. All metal parts shall be electrically grounded.
The following characteristics are also to be considered:
 The plant equipment is to be designed with the ergonomics considerations in mind; good safe access is to
be provided for all elements that require usual operation or inspections.
 All materials regardless of size or importance shall comply with durability and material selection criteria to
ensure fit for purpose.
The main equipment, which could be damaged in case of seism or due to the operation cycle, shall be mounted with
expansion joints to ease the assembly and provide security against vibrations.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
13 / 32
5.2 VESSELS
All tanks, vessels, chambers and manholes shall be suitably protected to prevent water ingress.
5.2.1 PRESSURE VESSELS
Pressure vessels shall be designed fabricated with non-corroding materials, with side entry feed and concentrate
ports and connections. The pressure vessels shall have all necessary adaptors, shims, spacers, or other fittings, for a
complete and functional system.
Pressure Vessels are to be designed under ASME section VIII Division 1 or under PED, European Pressure
Equipment regulation.
A certified copy of the production test data for each pressure vessel shall be provided. The pressure vessels shall be
compatible with the membrane elements, and all necessary internal and external components shall be provided for a
fully operational system.
For a vessel protected by an upstream relief valve, DP shall be at least equal to the set pressure of that relief valve.
5.2.2 TANKS
All tanks shall be designed with best industry practices in terms of drainage, accessibility.
Tanks shall be provided at least with overflow, vent (if required), access manhole and low point drain.
5.3 ACCESS
The general layout of equipment shall ensure adequate accessibility to allow regular operating and maintenance
tasks to be performed.
Access platforms shall be provided for major plant components, which cannot be operated or maintained from floor
level. Stairways shall be provided for access.
Access routes shall be provided for the removal of large plant components on trolleys or similar handling
appliances.
All process equipment shall be provided with a suitable quantity and distribution of isolatable drains, vents and
connections to service water to allow thorough flushing and draining in preparation for maintenance.
For equipment over 25 kg, jack screws, lifting lug or equivalent shall be provided.
Drains and vents shall be routed to the side of the package and will be properly isolated.
5.4 ALUMINIUM PLATES AND SECTIONS
All aluminium plates and sections shall be aggressive corrosion resistant.
manufactures according to EN 573 - DIN 2642
The aluminium Slip-On will be
5.5 STAINLESS STEEL
All items fabricated from stainless steel shall be manufactured according to AISI 304 or AISI 316, according to the
design to assure the corrosion resistant in each case.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
14 / 32
5.6 FABRICATION
5.6.1 METAL WORK
This Section applies to all fabricated carbon steel and aluminium process equipment metalwork which is
incorporated into the Works. Fabrication of metalwork items shall be carried out in accordance with EN1993-1-1
Eurocode 3 or international equivalent.
Metalwork shall be fitted accurately. Where appropriate, measurements shall be confirmed on site, prior to
fabrication. All welding shall be continuous full penetration butt welds or fillet welds. All fillet welds shall be full
seal welds. Spot welding or stitch welding shall not be utilised. Machined, cut or sheared edges shall be filed or
ground and shall be smooth and free of burrs and sharp edges. Welds in carbon or low alloy shall be chipped and
brushed free of slag before surface preparation for painting or galvanizing occurs.
5.6.2 STORAGE
All materials stored at the fabrication plant, and all fabricated metalwork, shall be supported above the ground so as
not to cause overstressing, properly protected from tarnishing or corrosion, and kept free of dirt, oil, grease, and
other foreign material.
6
PIPING
6.1 LINE SIZING
Lines shall be designed to convey the designated quantity of fluid (liquid or gas) at a velocity for the best
performance considering the back pressure.
If there is not a specific requirement, the following typical velocities shall be considered:
Water:
Material
GRP/HDPE
Stainless steel
Velocity (m/s)
3
2-4
Air:
Material
Velocity (m/s)
Stainless steel
12 (1)
Note 1: Maximum velocity in main air collectors shall be 20 m/s.
Lines shall be selected with consideration of the pipe relative roughness in order to absorb the minimum pumping
energy.
6.2 ALLOWABLE PRESSURE DROP
Process critical piping systems shall be fully analyzed (and sizes confirmed) for pressure losses resulting from
friction, elevation and pipe fittings.
The actual pressure drop, and hence line size, shall be confirmed with detailed calculations of process critical lines.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
15 / 32
6.3 PIPING MATERIALS
6.3.1 METALLIC PIPING
6.3.1.1. General
Selection and specification of material shall take account of the following:
- Fluid conditions (e.g., % solids, pH levels, chloride levels, erosiveness).
- Phenomena such as galvanic and other forms of localized corrosion.
- Environmental and Stress Corrosion Cracking.
- Intergranular Corrosion.
- Final material selection shall be specified in particular specifications and data sheets.
6.3.1.2. Flanges
 Flange Standards
All pipework associated with the pumping unit and associated fittings shall be flanged to PN10 or
greater in accordance with ISO 7005-2 (CI or DI) and ISO 7005-1 (Steel).
 Flange Types
Flanges should normally be slip on or weld neck type up to PN10. Weld neck flanges are only to be
used where welding directly to butt weld fittings such as an elbow or tee.
Pipe flange bolting patterns shall straddle pipe centrelines.
6.3.1.3. Fittings
Fittings shall conform to the requirements of the relevant Piping Material Class.
Fabricated branch connections shall be permitted, where supporting calculations are provided, as defined in the
branch connection table for each Piping Material Class. The branch table nominates the type of branch for every
combination of header and branch size for each material type.
6.3.1.4. Joints
Butt welded joints shall be used generally for stainless steels. These materials joints are in services susceptible to
crevice corrosion.
For stainless steel piping in a service not prone to crevice corrosion, socket weld joints shall be used in sizes DN 50
and smaller due to high cost and limited availability of socket weld fittings in larger sizes.
6.3.2 NON-METALLIC PIPING
6.3.2.1. General
Selection and specification of material shall take account of the following conditions:
- Increase in temperature due to solar radiation.
- Reaction with strong acids and alkalis.
- Compatibility with service fluid.
- Support availability and the facility to absorb the increased thermal expansion of the pipe.
- Effects of ultra violet radiation and fire.
- Creep.
- Cost.
- Surge potential.
- Corrosion and erosion.
- Fatigue.
- Shear Stress.
- Local buckling.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
16 / 32
6.3.2.2. Flange Backing Ring
All pipework associated with the pumping unit and associated fittings shall be flanged to PN10 or greater in
accordance with ISO 7005-2 (CI or DI) and ISO 7005-1 (Steel).
Backing rings for non-metallic flanged joints shall be made from polypropylene, coated carbon steel, 316 stainless
steel, hot dip galvanize (HDG) or plastic and shall be suitable for the plant environment.
6.3.2.3. Fittings
Fittings shall be injection moulded from the PVC, PE100, PP, ABS or PVDF. Fittings shall be rated to at least the
pipe rating.
6.4 SAFETY SHOWER AND EYEWASH
A safety shower and eyewash shall be installed adjacent to any acid, caustic or dangerous material handling
equipment in accordance with the relevant international safety standards.
The safety shower and eyewash stations are piped to potable water supply. Locations of safety showers shall be
decided based on operational requirements. Stations in finished areas shall be supplied with floor drains; stations in
process areas shall be curbed with drainage directed to a safe location.
Safety shower layout shall provide a clear and unobstructed path from the hazard location to the station.
6.5 PIPING SUPPORTS
Pipe Supports location shall be detailed on plans, elevations and support detail drawings. Standard support drawings
shall be produced where required.
The stresses in small piping connections shall be reduced to a minimum by adequate supporting. Extra supports and
bracing shall be designed to minimize vibration.
Piping around control valves and in-line instrumentation shall be adequately supported to minimize vibration and
stress at these devices.
Piping sections requiring frequent dismantling for maintenance, such as for the installation of blinds, shall be
provided with permanent supports for the dismantled condition.
Pipe supports shall be made of carbon steel coated. Pipe supports will be provided with neoprene band between the
pipe and the support in order to avoid corrosion.
6.5.1 SPECIAL PIPE SUPPORTS
Special pipe supports shall be numbered, listed, indicated on drawings and controlled by area.
Each special pipe support shall be allocated an individual reference and sequentially numbered. The use of unique
reference numbers is to assist in the control of the supports during design and construction.
7
STRUCTURAL DESIGN FOR EQUIPMENT
7.1 GENERAL
Structural supporting steel work shall comply with EN 1993-1-1 Eurocode 3 or international equivalent.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
17 / 32
7.2 LOADS
7.2.1 PERMANENT LOADS (W)
Permanent structures of equipment, shall be designed to resist expected permanent loads as specified in EN 1993-11 Eurocode 3 or an international equivalent.
7.2.2 VARIABLE LOADS (W)
Permanent structures of equipment, shall be designed to resist expected variable loads as specified in EN 1993-1-1
Eurocode 3 or an international equivalent.
7.2.3 EARTHQUAKE LOADS (E)
The seismic parameters shall be in accordance with TCVN 9386:2012.
8
PROVISIÓN FOR HANDLING EQUIPMENT
Equipment/plant shall be designed to enable operational maintenance to be carried out by the plant operators rather
than specialised sub-contractors or trades people wherever possible. Lifting equipment with appropriate safe
working load capacity shall be provided where health and safety requirements preclude manual handling. The
maximum weight of manually-removable covers and grating panels shall be 25 kg. Buildings in which lifting
equipment is provided shall be of an adequate height to allow lifting above other items of equipment and onto
vehicles.
All parts of the plant with a mass greater than 25 kg shall have provision for lifting, slinging and handling during
erection and overhaul or maintenance.
Lifting procedures shall be supplied for all equipment weighting more than 2 Tonne or larger than 3 m³.
9
SPECIAL TOOLS
Any special tools which may be necessary to enable the maintenance dismantling and attention to all parts requiring
periodic maintenance or replacement to be carried out expeditiously shall be supplied with the equipment.
The use of any special tools shall be clearly identified in the Operation and Maintenance manuals provided by
suppliers.
10 NOISE AND VIBRATION
The equipment and room design shall comply with the QCVN 26:2010/BTNMT National Technical Regulation on
noise and vibration.
10.1 SOUND PRESSURE LEVEL
The equipment noise level during operation shall not exceed an overall weighted sound pressure LAeq, 8 h of 85
dB(A) (8 hour exposure average of 85 dB(A)) when measured no further than 1 meter from the wall of the
equipment.
Where this requirement cannot be met, this shall specifically be indicated.
A noise attenuating enclosure or other sound insulating material should be provided to bring the sound pressure
level down to stated limits necessary for the protection of workers and the public.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
GENERAL MECHANICAL DESIGN
CRITERIA
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
Rev.
A
Date
2020-07-31
Page
18 / 32
10.2 NOISE SURVEY
A noise survey shall be performed prior to commencing construction to determine the current noise level at the site,
and demonstrate that the completed WWTP at its full operation shall not increase DENR standards for Noise Levels
in General Areas included in table below above 3 dB(A).
Table 1 – Permissible noise limits (in decibel), dB(A) (QCVN 26:2010/BTNMT)
Nº
1
2
Area
Special areas
Usual areas
From 6:00 to 21:00
55
70
From 21:00 to 6:00
45
55
10.3 NOISE CONTROL
Noise levels shall be contained by appropriate equipment design.
Acoustic enclosures shall form an integral part of the equipment, and shall not adversely affect the safety or function
of equipment.
The soundproofing enclosures shall not impede the flow of cooling air when fully installed.
The acoustic enclosure shall be constructed so that it can be easily removed for maintenance purposes. The
enclosure shall have locks/latches to keep the enclosure closed when it is over the equipment.
Normal operation shall be possible without opening or removing enclosure. Hinged access doors shall be provided
for easy access for routine inspection and maintenance or lifting lugs where overhead gantry is available.
The material used shall not be vulnerable to the high temperature inside the enclosure.
10.4 THERMAL AND ACOUSTIC INSULATION
10.4.1 GENERAL
Insulation shall be provided for personnel protection, for reduction of noise emission and for process requirements.
All insulated equipment shall be provided with corrosion resistant aluminum sheath. Insulation for outdoor
installations shall be rain and dustproof. Tank and duct tops shall be provided with insulation strong enough to
support a man's weight.
The sheets shall be secured and connected at the longitudinal seams with self tapping screws (five screws per
meter). At the longitudinal and circumferential joints, the sheets shall overlap by at least 50 mm so that water will
run off and not soak into the insulation material. The overlap shall be in the same direction of possible water flow,
so that penetration of water is avoided. The seams and penetrations of any sheet metal insulating jacket installed
outdoors shall be sealed against water by means of suitable insulating tape.
10.4.2 INSULATION OF INDIVIDUAL ITEMS
All flanges, valves and fittings shall be provided with two piece or multi part combination caps made of sheet metal
of the specified thickness and a steel plate galvanized on both sides of at least 275 g/m².
The shaped caps of the fittings shall be made longer by approximately twice the insulation thickness so that the
welding seams will be exposed after removal of the cap. Where possible, these caps shall be fitted with a clamping
strip or lever hook to facilitate assembly.
Tanks and equipment shall be insulated in the same way as pipes, except that the insulating material may not be
attached by wire but by using strong galvanized steel bands. The tank manufacturer shall furnish insulating supports.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
19 / 32
Expansion joints shall be insulated with detachable, two piece or multi part combination caps.
The insulation mats are to be secured in the sheet metal caps by means of hooks and clips.
10.4.3 VIBRATION
Impermissible transmission of vibrations shall be prevented, or at least reduced, by mounting equipment on
vibration isolators and, as far as possible, by decoupling pipelines to and from the equipment.
Moreover, all plant components shall be so designed that impermissible flowing media cannot cause high vibrations.
11 LUBRICATION
The equipment design shall ensure cross contamination of lubricants into the process fluid is not possible.
11.1 FIRST FILL & FLUSH
Flushing and first fill of lubricating oil or grease for all parts of the work shall be provided with the equipment.
11.2 RECOMMENDATION BY SUPPLIER
A list of recommended oils and greases, frequency and method of lubrication for the equipment shall be provided
and included in the equipment Manual.
11.3 GREASE LUBRICATION POINTS
Grease lubrication points shall be fitted with covered nipples. Greasing points shall be in an accessible position at
operator level.
Grease lubricator shall be fitted nipples complying with BS 1486 or an equivalent standard.
Lubrication units shall be supplied clean and flushed and with all openings sealed for long storage and to be
removed just before first filling.
12 PROTECTION OF METAL WORK FROM CORROSION
12.1 GENERAL
The local environmental conditions at Nhieu Loc Thi Nghe Wastewater Treatment plant project site are potentially
corrosive. Mechanical equipment that is not manufactured from corrosive resistant material shall be supplied with a
protective coating under specifications of ISO or equivalent British / American/ Japanese Standards.
Suppliers shall provide details of the external coatings provided including:
-
Surface preparation prior to coating: type, standard etc.
The type of coating(s) and dry film thickness (microns).
Repair and maintenance procedures.
Manufacturers with international experience shall only supply coating material and their products can be obtained
internationally.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
20 / 32
Regarding maintenance work (storage), application and supervision of coating work, choice of coating suppliers
should be minimized. At any rate, similar parts of structures/components (such as structural steel containers, piping,
etc.) shall only be coated with products of one individual manufacturer.
The materials and equipment used, the methods of application and the quality of work shall at all times be subject to
the inspection and approval of the Employer or his Representative.
12.2 SURFACE PREPARATION AND CLEANING OF SURFACES IN THE SHOP
Prior to blasting, areas have to be cleaned from:
 oil,
 grease,
 paint residues,
 splatters,
 mill scale,
 welding splashes and,
 welding slag.
Sharp edges have to be rounded off.
Contamination caused by salts, acids and alkali solutions shall be eliminated by rinsing with water up to a pH value
of 6-8.
The preparation of substrates shall be carried out on the basis of the specifications of ISO 12944 part 4 and ISO
8501 or equivalent British / American/ Japanese Standards.
After blasting, an anchor profile of 25-50 μ shall be achieved. Blasted surfaces have to be provided with a prime
coat of the considered coating system immediately after blasting.
Steel work protected by shop primer after arrival on site must be cleaned of salt, sand, oil, etc. before the first coat of
paint is applied on site. Shop primer damaged during transport must be rectified by blast cleaning and coating before
application of the site coats.
Wood surfaces shall be sanded clean. All nail holes shall be puttied and sanded before priming. If a protective
coating of concrete is required, concrete shall be allowed to cure before painting.
Transport and erection damages, as well as damages which result out of additional welding have to be repaired as
soon as possible. The damaged areas have to be de rusted with rotating or steel brushes, abrasive wheels, abrasive
blasting according to ISO 8501-1, or equivalent International Standards.
12.3 CLEANING OF PRIME AND INTERMEDIATE COATS (IF REQUIRED)
To prevent contamination by mineral oil products, areas with prime and intermediate coat have to be treated with
suitable cleaning agent. Cleaning has to be done free of residues, e.g. with alkaline detergents and thorough washing
done with fresh water. Rusty spots have to be removed according to required purity. Metallic areas, which are
provided with temporary corrosion protection, have to be cleaned. No oxidation products shall remain on the
surface. Furthermore, care should be given that on hot components no destructive nor reaction products will be
released when heating which could injure insulation.
12.4 APPLICATION PROCEDURE
When using the provided coating material, strict adherence to all application instructions given in product data of
coating manufacturer is necessary. To obtain the maximum performance, technical data as well as application
instructions for the individual coating material have to be strictly followed.
For a multi layer coating system, each layer has to have a different color shade in order to clearly identify number of
coats applied.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
21 / 32
The last finish coat has to be applied in the specified color shade.
The interval between applying the different coats has to follow the supplier's instructions. Each layer has to be
cleaned and released from spray dust before the next layer will be applied. Prior to applying a further layer, the last
one has to be repaired. All coatings have to be applied without retarding.
Following application procedures are allowed:

Prime coats by airless spray: areas like disconnection, angles, corners, etc., which are difficult to be
reached, can be applied by brush or roller;

Repair of prime coat by brush;

Finish coats;
-
at works: by airless pray, roller or brush;
at site: by roller or brush or airless spray.
When applying coating systems by roller, rollers have to be of the kind and quality that makes an appropriate
application possible.
Control areas in accordance with the coating supplier's instructions have to be applied. For this procedure, a
schedule for control areas has to be prepared by the Contractor and coating supplier which corresponds with the
requirements of the warranty agreement.
Number and performance of the control areas have to be done in accordance with ISO 12944 part 7 or equivalent
British/American/Japan Standards, and have to be documented in writing.
All specified dry film thickness (DFT) are minimum thickness.
Checkered plates, snap plates, etc. do not have to be covered with adhesive tape, but have to be coated with stripping
coat in a dry film thickness of at least 150 μm.
Edging lines on steel structure have to be taped prior to application and after blasting in sufficient width or have to
be protected with varnish before application. Thickness of prime coat may be 50μm max.
During repairing works at site on shop primed structures, it is important that different coats will have different color
shades. Number of layers have to be the same as the original coating system to be used.
Application of temporary primer on structures which have to be insulated has to be in accordance with a sufficient
corrosion protection for the period of storage depending on the erection time.
12.5 GALVANIZING
Galvanizing work shall conform in all respects to ISO 1461 or BS 729, BS 3083 and BSCP 2008 and shall be
performed by the hot dip process unless otherwise specified.
It is essential that details of steel assemblies which are to be hot dip galvanized should be designed to suit the
requirements of the process. They should be in accordance with BS 4479and ISO 12944.
Vent holes and drain holes shall be provided to avoid high internal pressures and air locks during immersion and to
ensure that molten zinc is not retained in pockets during withdrawal.
Careful cleaning of welds is necessary before welded assemblies are dipped. All defects of the steel surface
including cracks, surface laminations, and laps and folds shall be removed in accordance with BS 4360. All drilling,
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
22 / 32
cutting, welding, forming and final fabrication of unit members and assemblies shall be completed, where feasible,
before the structures are galvanized.
The minimum average coating weight shall be as specified in Table 1 of BS 729. Structural steel items shall be first
grit blasted to BS 4232, second quality, (Sa 2½) or pickled in a bath, and the minimum average coating weight on
steel sections 5 mm thick and over shall be 900 g/m², on steel sections 2 5 mm thick 600 g/m².
Galvanized contact surfaces to be joined by high tensile friction grip bolts shall be roughened before assembly so
that the required slip factor (defined in BS 3294 part 1 and BS 4604 part 1) is achieved. Care shall be taken to ensure
that the roughening is confined to the area of the mating faces.
Protected slings must be used for off loading and erection. Galvanized work which is to be stored at the works or on
site shall be stacked so as to provide adequate ventilation of all surfaces to avoid wet storage staining (white rust).
Small areas of the galvanized coating damaged in any way shall be restored by:


Cleaning the area of any weld slag and thorough wire brushing to give a clean surface.
The application of two coats of zinc rich paint, or the application of a low melting point zinc alloy repair
rod or powder to the damaged area, which is heated to 300°C.
Connections between galvanized surfaces and copper, copper alloy or aluminum surfaces shall be protected by
suitable tape wrapping.
12.6 COATING SYSTEM
The protecting coating shall comply at least with the table below.
Coating Systems
System
No.
1
2
3
4
Structural steel
works, piping,
vessel, tanks
INDOOR
Structural steel
works, piping,
vessel, tanks
OUTDOOR
Up to 120
SA 2.5
Primer
Finish
1
1
Zinc-Epoxy
Epoxy high
solid
Up to 120
SA 2.5
Primer
Intermediate
Finish
1
1 -2
1
80
160
80
80
160
80
290
Piping, tanks etc.
INDOOR and
OUTDOOR,
Insulated
Pumps, motors,
other equipment
OUTDOOR
Up to 120
SA 2.5
Primer
1
Zinc-Epoxy
Epoxy high
solid
2-Comp.
Polyurethane
Zinc-Epoxy
50
50
Up to 120 or
according
manufacture
standards
SA 2.5
Primer
Intermediate
Finish
1
1
1
Zinc-Epoxy
Epoxy high
solid
2-Comp.
Polyurethane
80
110
50
80
110
50
240
Zinc-Epoxy
Epoxy high
solid
80
50
80
50
130
Zinc-Epoxy
75
75
Zinc
Ethysilicate
Silicone
Acrylic
75
50
75
100
175
Pumps, motors,
other equipment
INDOOR
Up to 120
6
Piping, reactors
OUTDOOR
Insulated
Stacks
OUTDOOR
>120
7
Dry film
thickness
(DFT) per
coat μm
80
80
Surface
preparation
5
VN01C2-ME-RP-1001
<120
<200
Coating
system
No.
of
coats
Temperature
(°C)
Surface location
Or according manufacture standards
SA 2.5
Primer
1
Finish
1
Or according manufacture standards
SA 2.5
Primer
1
SA 2.5
Primer
Finish
1
2
Generic type
Total
DFT μm
80
80
160
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
23 / 32
Coating Systems
System
No.
Surface location
Temperature
(°C)
Surface
preparation
8
Steel surfaces Uninsulated
200 -450
SA 2.5
9
Galvanized
surface
Up to 120
10
Steel surface
permanently in
contact with
water, also
seawater splash
zone
Medium
temperature
up to 69 oC
Mechanical
cleaning from
contaminants
and zinc salts
by means of
washing or
steam jetting or
sweep blasting
with fine sand
SA 2.5
Coating
system
No.
of
coats
Primer
Finish
1
2
When finish
coat is
required,
such as sea
climate with
chloride
exposure
1
Prime and
finish coat in
one
1
Generic type
Zinc
Ethysilicate
Silicone
Acrylic
Epoxy high
solid*
Glassfake
reinforced
High solid
epoxy
Dry film
thickness
(DFT) per
coat μm
75
25
Total
DFT μm
75
50
125
125
125
500
500
12.7 DESIGN CORROSION CONTROL & DURABILITY
Proper planning and careful attention to corrosion protection at the design stage are essential to minimise corrosion
and simplify future maintenance. All design work therefore has to be performed with corrosion prevention in mind
by avoiding sharp edges, crevices, rough welds, corners, depression and pockets dead legs and areas subject to
stagnation.
The detailed design should as far as possible avoid all features which would make it possible for water or foreign
matter to accumulate, and therefore accelerate the failure of coatings. Where this is not possible, drainage holes
should be provided or flushing methodology proposed. The structure should be designed to facilitate the application
of maintenance coatings in the future.
Examples of design shortcomings that are to be avoided are as follows:
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
24 / 32
Poor access, back to back
angles, sharp corners and
profiles should be avoided
to ensure adequate surface
preparation, access for
coating is provided.
Figure 1- Effects of design on the painting and cleaning of structures
Structural members should
allow good drainage i.e. be
designed to avoid retention
of fluids.
Figure -2 - Effects of design on drainage
Ensure gaskets are well fitted
with no overhang or under-hang
which can create crevices and
promote crevice corrosion,
especially in stainless steels.
Figure -3 - Effects of untrimmed gaskets
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
25 / 32
Particularly important for
metallic vessels, it is
imperative that the design
does
not
allow
the
accumulation of liquids
under the base of the tank.
Figure -4 - Effects of poor drainage
Similar to fig 12-4 above, tanks
should be designed as free
draining. Important for coated
steel tanks, but equally important
for non-metallic and stainless
steel tanks, as concentration
effects can significantly change
the corrosion characteristics of the
fluid.
Figure-5 - Effects of poor drainage
Structural components should
be designed to avoid retention
of fluids.
Figure-6 - Effects of poor drainage
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
26 / 32
13 PRE-SERVICE CLEANING AND PROTECTION OF SYSTEM EQUIPMENT
This clause covers mechanical and pre service cleaning and protection of the items and equipment at the
Manufacturer's workshop and at site that are not subsequently to be painted.
Mechanical cleaning as opposed to alternative chemical cleaning is the preferred method for workshop cleaning
except where this is precluded by design or access considerations.
Machined surfaces shall be protected during the cleaning operations. For re cleaning, small areas, hand cleaning by
wire brushing may be permitted. Wire brushes used on austenitic materials shall have austenitic steel bristles.
Austenitic stainless steels, copper and aluminum alloys, cast iron, bimetallic and metallic/plastic items, and
components fabricated by spot welding or riveting shall not be chemically cleaned. All weld areas shall be suitably
stress relieved before chemical cleaning.
14 SAFETY
The consideration of personnel safety during construction, ongoing operation and maintenance, in the design,
selection and installation is paramount.
It shall assure safe operation and provide adequate access for maintenance activities, minimize consequence due to
fire and avoid congestion.
14.1 PROTECTION OF PERSONNEL
Emergency showers, eye wash stations and emergency deluge bays shall be designed, specified and located to suit
each particular circumstance and to maximize their effectiveness. Water temperature, deluge rate and coverage,
supply pressure, accessibility and remote indication of use shall be considered.
All piping trenches or drainage trenches shall be covered to minimize accidental fall risk. Openings in the grating
shall be enclosed in handrails.
14.2 SAFETY OF MACHINERY
All packaged equipment shall fully meet the safety standards of the Socialist Republic of Vietnam.
All guards, notices and warning lights necessary to afford protection from electrical apparatus, conductors, moving
parts of machinery, hot surfaces etc. shall be provided to prevent risk of injury to personnel.
14.3 INTERLOCKS
Inspection doors shall be provided by the Supplier where required for routine inspections. All guards shall be
capable of being removed without disturbing other parts of the plant. All inspection doors shall be fitted with
interlocks that shall prevent the machines from running when opened if not adequately guarded or other means to
prevent injury to personnel.
14.4 INSPECTION OPENINGS
Inspection openings shall have warning signs to advise personnel of potential hazards that may be exposed when
opened. Where equipment must be isolated, drained, depressurised or any other procedure to make equipment safe
for inspection, e.g. confined spaces, this shall be stated on the warning notice at the opening.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
27 / 32
Inspection openings that may expose potential hazards which cannot be adequately controlled by “Basic PPE” shall
not be operable by hand without the use of tools or keys. For the purposes of this requirement “Basic PPE” means
safety glasses and earplugs.
14.5 COUPLING GUARDS
Coupling guards shall be provided and shall be rigidly fixed over the coupling. The coupling guard shall be designed
so that it can be readily removed. No body parts shall be able to come in contact with rotating parts. Guards shall
be made from materials complying with the durability requirements to provide the asset life.
15 FASTENERS
15.1 MECHANICAL FASTENERS
15.1.1 MATERIALS
All fasteners shall be of materials suitable to achieve the durability specified herein.
The type of fasteners to be used in plant depends on their location and environment as specified in equipment data
sheets.
In general fasteners for mechanical plant shall be corrosion resistant stainless steel, except for equipment with type
test certificates such as electric motors where surface coating protection is to be provided.
Unless stated otherwise the following fasteners shall be used:
-
Metal fasteners of dissimilar metals from the base structures must be isolated to minimize the possibility of
galvanic corrosion.
All fasteners including bolts, studs, nuts and washers shall be marked to be able to identify and segregate
different grades of stainless steel
Where stainless steel fasteners are used in contact with HDG, insulating washers or joints are required.
Bolting should comply with AISI316 or a similar recognized international standard.
15.2 PASSIVATION OF STAINLESS STEEL FASTENERS
Stainless steel fasteners shall be passivated after manufacture and prior to installation.
16 ERECTION MARKS
All apparatus and fittings shall be marked or stamped or otherwise permanently labelled before leaving the site
where the equipment has been fabricated. This shall be a distinguishing number and/or letter corresponding to the
distinguishing number and/or letter drawings or material list.
The identification of component members shall correspond to the distinguishing numbers and/or letters shown on
approved drawings and shall be in the location shown on these drawings.
The erection marks shall be clearly legible after galvanising or painting and shall be legible from a distance of at
least 2 metres. Where stamps are used to identify components the stamping must be ringed with paint to assist
location.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
28 / 32
17 LABELS
Each installed equipment shall be labelled for permanent identification. All labels, nameplates, instruction, and
warning plates shall be securely fixed to items of plant and equipment with stainless steel rivets, plated self-tapping
screws or other means except adhesives.
All inscriptions shall be in the English and Vietnamese language.
For safety signs ISO 3864 (Safety Colours and Safety Signs Information) shall be applied.
18 PIPELINE IDENTIFICATION
Pipe Markers in the form of appropriately coloured printed labels shall be affixed on all pipes according to ASM
A13.1 or BS 1710 – Specification for Identification of Pipelines and Services . The printed labels shall show words
indicating the contents of the pipe and any associated hazardous aspect of the pipe, e.g. high pressure, toxic, strong
acidity. The letters shall be in a colour that is clearly visible, identification code for pipeline according to media,
with the German colors tone system RAL 840 HR. Arrows shall be provided to show the direction of flow.
The outside surfaces of pipes shall not be painted to provide identification of their contents. Painting of pipes can
create significant quantity of future maintenance work and is also inappropriate for some applications (stainless steel
pipes). Furthermore, when utilising the colour coding, in some cases different services will be given the same
identification colour as a large variety of chemicals will be used at this plant. Instead of painted pipe, localized paint
marks or colour stickers shall be used.
The labels shall be both UV and weather resistant and shall not fade or need replacement more frequently than once
every fifteen years.
Piping shall be marked on both ends.
19 NAMEPLATES
Nameplates for plant and equipment identification and record purposes shall be manufactured from stainless steel or
aluminum with a mat or satin finish, and engraved with black lettering of a size which is legible from the working
position.
Warning plates shall be manufactured from stainless steel or aluminum engraved red white lettering on a white
background and sited in the position where they afford maximum safety of personnel.
All equipment within panels and desks shall be individually identified by satin or mat finish stainless steel or
aluminum labels, or laminated plastic labels to the extent approved by the owner's Project Manager.
Nameplates fixings shall be such as to allow ready replacement without damage to the label or the fixing.
Adhesive nameplates should avoided unless specific advantages for particular applications.
The label shall be affixed to the specific item of equipment so that it may be conveniently read when in the installed
position and should be attached to a principal component of the equipment item so that it is not misplaced or
inadvertently discarded on a replacement part during overhaul.
Pump casing hydrostatic test pressures and serial number shall be stamped on the casings and the direction of
rotation of pump shall be clearly indicated by an arrow cast on the castings.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
Rev.
A
Date
2020-07-31
Page
29 / 32
Each valve shall be fitted with a stainless steel or aluminum nameplate indicating the valve service and reference
number. Valve direction of closure should be clearly and permanently marked on the hand wheel.
Information shall be provided by the Supplier for the various items as follows:
VN01C2-ME-RP-1001
REPORT
GENERAL MECHANICAL DESIGN CRITERIA
DESIGN, BUILD AND OPERATION OF THE NLTN
WWTP, HCMC
Cranes,
davits, other
lifting
equipment
Centrifuges,
conveyors
and
mechanisms
Heaters &
coolers
Mixers
30/32
Compressors,
blowers
Page:
Filters,
screens,
strainers
2020-07-31
Chemical
plant
Date:
Tanks &
other
vesselsA
A
Venturi’s,
ejectors,
diffusers,
flowmeters
Rev:
Pumps
AVJ-A000-ME-RPT-1001
Valves,
penstocks
Equipment→
Ref:
Manufacturer
X
X
X
X
X
X
X
X
X
X
X
Model / Type
X
X
X
X
X
X
X
X
X
X
X
Serial number
X
X
X
X
X
X
X
X
X
X
X
Nominal size / capacity
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
↓ Parameter
X
Design standard
X
X
Hydrostatic test pressure
X
X
Flange Specification
X
X
Design Pressure (bar) and temperature (°C)
Material
X
NPSHr (m) at duty point
X
Relief valve pressure set point
X
X
X
X
Flow rate (m3/h)
X
X
Discharge head (bar)
X
X
Speed (RPM)
X
Voltage/Phase/Hz
X
X
X
X
X
X
X
X
X
X
X
X
X
Duty point power (kW)
Year, country of manufacture
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Impeller diameter (mm)
Suction and discharge diameters (mm)
Mass (empty/ full)
X
X
X
Safe Working Load
Note A: Other vessels include receivers, pressure vessels, surge vessels, pulsation dampers and silos.
VN01C2-ME-RP-1001
X
X
X
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Rev.
A
Date
2020-07-31
Page
31 / 32
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
20 INSPECTION AND TESTING
20.1 SCOPE
The scope of the inspection and testing to validate the design shall be defined in the equipment specifications and or
data sheets in the appendix called Inspection Point Program (IPP).
Equipment specific inspection and test plans including the proposed workshop, factory acceptance and precommissioning test shall be submitted. This documentation shall define the responsibility matrix. All required
workshop tests and factory acceptance tests of the equipment shall be performed.
Equipment assemblies shall be tested as a single combined unit.
20.2 STAGES OF TESTING




Workshop Tests conducted during the manufacture of the equipment.
Factory Acceptance Tests (FAT) conducted at completion of manufacture prior to dispatch. FAT shall
include the compilation of all Workshop Test records for the equipment.
Pre-commissioning tests of equipment following completion of construction.
When identified in the IPP, Acciona - Vinci (AVJ) shall advise for witness test and or witness point
release.
20.3 INSPECTION POINTS PROGRAM (IPP)
All test plans and procedures for workshop tests, factory acceptance tests, pre-commissioning tests as applicable,
and prior to commencement of each stage of work shall be submitted by the AVJ Representative.
Any additional tests that may be required to confirm that the equipment complies with the Specifications shall be
performed in accordance to the mechanical equipment specific IPP’s as appended in their relevant specification and
or data sheet.
20.4 GENERAL REQUIREMENTS FOR TESTING
Tests and inspections, unless otherwise specified, shall be in accordance with the relevant design standard. Any
deviation to PPI’s specified standards shall be transmitted for approval.
All relevant information and experiences gained during tests, including readings such as flow, noise, vibration,
power draw, shall be properly documented, and included in an appendix of the Operations and Maintenance
Manuals and work-as-executed drawings.
20.5 FACTORY ACCEPTANCE TESTION AND INSPECTION
20.5.1 TEST PLAN AND PROCEDURE
An Inspection Points Program (IPP), and procedures for Factory Acceptance Testing (FAT) and inspection covering
each type of equipment to be tested are shown in the relevant mechanical equipment Inspection Points Program.
VN01C2-ME-RP-1001
REPORT
Ref:
AVJ-A000-ME-RPT-1001
Rev.
A
Date
2020-07-31
Page
32 / 32
Leader
DESIGN, BUILD AND
OPERATION OF THE NLTN
WWTP, HCMC
GENERAL MECHANICAL DESIGN
CRITERIA
20.5.2 FAT AND INSPECTION REPORT
All documentation, including IPP’s, material certificates and performance curves shall be included in the Factory
Acceptance Testing and Inspection Report. A copy of the final version of this report shall be included as an
appendix of the relevant Operation and Maintenance manuals.
21 PRE-COMMISSIONING
21.1 PRE-COMMISSIONING INSPECTIONS AND TESTS
A pre-commissioning inspection and test plan for the equipment shall also be provided for the equipment in the
commissioning manual.
Pre-commissioning entails conducting tests and simulations for the purpose of proving that a particular piece of
equipment, part of the plant or a component is complete, fully functioning and ready for operational/performance
tests and operation. Pre-commissioning includes dry testing and wet testing, including all aspects of component
operation such as hydraulic, electrical, mechanical, instrumentation, software and control systems associated with or
linked to the Component.
VN01C2-ME-RP-1001