ENGINEERING STANDARD
Design Criteria for Plant Layout
3PI01001
Rev.3
Page 1 of 10
Uncontrolled copy unless a distribution list is included in this document: Print Date: 28 April 2025
Complete Revision: EPS-01131950
1.
PURPOSE
1.1
This engineering standard defines the basic design requirements for plant layouts.
2.
SCOPE
2.1
This standard applies to all plants designed, owned, and operated by Air Products. Cylinder fill
activities are not covered by this guideline.
2.2
This standard applies to sale of equipment, unless the customer's requirements are more
stringent.
3.
MINIMUM TECHNICAL REQUIREMENTS
3.1
Plant layout shall be the optimum combination of economy, operability, and basic safety
considerations.
3.2
Process vents shall be located in accordance with 3PI25010 “Venting of Nontoxic and
Nonflammable Substances” and 3PI25011 “Venting of Buoyant Flammable Gases”, unless local
regulations are more stringent, or specific regional codes apply.
3.3
Climatic Conditions:
3.3.1
Vents shall be located to prevent carryover onto residential property or other zoned areas, and
onto platforms, stairs, building openings and air intakes, and operating areas within the
facility.
3.3.2
Cooling towers shall be located so that the prevailing wind does not carry the drift onto the
plant or into areas in which it could cause icing, accelerate external corrosion of plant
structure or equipment, or where visibility impairment could be hazardous (such as, causing
fog on neighboring roads). The concern for fogging also applies to ambient vaporizer back-up
systems. The cold vapor caused by normal operation causes a dense low-level fog, which can
drift for considerable distances causing poor visibility hazards both within the site boundary
and across adjacent sites and roadways.
3.3.3
Cooling towers, air compressor houses, and air separation units shall be located so that
flammable and/or corrosive gases and atmospheric particulates from neighboring process
plants, boiler chimneys, and other sources are not carried into the air intakes by the prevailing
wind.
3.4
Equipment, Utility, and Building Location
3.4.1
All equipment in Air Separation Plants shall have separation distances according to 3ES60101
“Safety Distance Criteria for Air Separation Plants”.
3.4.2
All equipment in HYCO and Gaseous Hydrogen Plants shall have separation distances
according to local regulations (e.g. NFPA) for flammable and toxic gases. This shall be
determined on a case by case basis.
© 2018 Air Products and Chemicals, Inc. All information herein is the property of Air Products unless another source is shown. This
document is classified as Air Products Internal Use Only, is subject to return on demand and must not be disclosed or reproduced
without prior written consent. This information may be subject to export controls. Disclosure contrary to U.S. law is prohibited.
Design Criteria for Plant Layout
3PI01001, Ошибка! Используйте вкладку "Главная" для применения Revision к тексту, который
должен здесь отображаться., Page 2 of 10
3.4.3
Heat exchangers shall be located to minimize connecting process lines and to use common
utility mains.
3.4.4
Storage systems separation distances shall comply with STD-ENG-ES012 “Separation
Distances for Storage Systems and Process Equipment” for North America plants.
3.4.5
Compression equipment shall be located to minimize interconnecting piping distances from
cold boxes or other equipment.
3.4.6
Deep water wells and waste water wells locations and siting shall be determined on a case-bycase basis, and shall comply with local regulations.
3.4.7
Electrical equipment shall have minimum clearances listed in Table 1 in areas where the NFPA
70 code is applicable. Where the NFPA 70 code is not applicable, electrical equipment shall
have minimum clearances in accordance with applicable local electrical code.
3.4.8
Ambient Vaporizers shall be spaced according to manufacturer’s recommendations. See Table
2 for required spacing around the outside of vaporizer banks.
3.5
Minimum personnel and equipment minimum safety clearances shall be according to Table 1
3.6
If lifting areas or wells are used, they shall be large enough for the largest piece of equipment
that will have to pass through them, and should be kept free of piping, cables, and other
minor equipment that could impede their proper use.
3.7
Roads
3.7.1
Layout of roads shall allow for both present and specified future traffic densities.
3.7.2
Primary roads shall not infringe on hazardous area classifications
3.7.3
Emergency access shall be provided to all areas of the process plant. Adequate access for
firefighting and other emergency service vehicles shall be provided in accordance with local
laws.
3.7.4
The number of road junctions, rail crossings, 90-degree turns, dead ends, and ramps should
be minimized. Turnaround or spur roads shall be provided at dead ends for vehicle turning.
3.7.5
Requirements for roads are contained in Table 3.
3.7.6
Areas in which a number of articulated vehicles will be loading or discharging at one time
should have a minimum depth of 36 m (120 ft) for angle parking, and a minimum of 44 m
(145 ft) for square parking, to allow vehicles to maneuver. The parking area dimensions and
shapes shall be determined on a case by case basis, according to parking frequencies and road
conditions.
3.7.7
A level area and a minimum straight length shall be provided at the approach and exit of each
scale.
3.7.7.1 For plants within the United States, state regulations require that level areas extend a
minimum 3m (10 ft) from the scale, and the straight length minimum shall be equal to the
length of the scale load platform.
3.7.7.2 For plants outside the United States, the local department of transportation should be
consulted for minimum level area length and straight length.
© 2018 Air Products and Chemicals, Inc. All information herein is the property of Air Products unless another source is shown. This
document is classified as Air Products Internal Use Only, is subject to return on demand and must not be disclosed or reproduced
without prior written consent. This information may be subject to export controls. Disclosure contrary to U.S. law is prohibited.
Design Criteria for Plant Layout
3PI01001, Ошибка! Используйте вкладку "Главная" для применения Revision к тексту, который
должен здесь отображаться., Page 3 of 10
3.8
The consequences of all probable plant emergencies shall be considered in the overall plant
layout.
3.9
All appropriate emergency equipment (for example, safety showers, eye wash stations, and air
packs) must be in safe, accessible locations that are as close to their anticipated use areas as
possible.
4.
REQUIRED SAFETY ENHANCEMENTS FOR AIR PRODUCTS FACILITIES
No.
Name
Category/
Reason Code
Safety
4.1
Cooling Tower Stand Pipe Clearance
Cooling tower stand pipes shall be considered a gaseous-effluent source. A minimum 6 m (20 ft)
horizontal clearance to adjacent platforms is required, excluding access areas provided with the
tower. See Table 1
4.2
Safety
Flares and Flammable Vents Location
The impact of radiant heat on personnel and in-plant equipment shall be studied by the safety
engineer, and the results of the analysis shall be used to locate flares and flammable vents
within the site.
4.3
Safety
Separation from Neighboring Third Part Plants
Equipment, buildings, and utility stations located in Air Products facilities shall be separated
from neighboring customers or third party plants in accordance with the recommendations of
the project hazard and operability study, and in accordance with the appropriate safety
distances for the separation of hazardous materials located outside of the battery limit.
Safety
Cryogenic Leak/Spill Prevention
4.4
Cryogenic liquid shall be prevented from exiting the site or entering the public drainage
systems. This can be accomplished by utilization of any combination of the following:

Central location of the storage tanks(s), pumps and piping systems on the site

Sloping of finished grade to direct flow

Site drainage/retention systems such as swales, and ponds

Flow containment details such as curbs and sluice gates
4.5
Safety
Equipment Layout for Noise Attenuation
Equipment layout shall be used to reduce the noise impact at fence lines and at work areas
within the plant. Storage tanks, cold boxes, and structures shall be used to shield equipment
that emits noise. Work areas include control room, terminal, and maintenance area.
4.6
Road Protection Near Vulnerable Plant Installations
Safety
If roads pass near vulnerable plant installations (for example, corrosive liquid tanks and pipe
bridge trestles), crash barrier protection such as standard highway guardrails shall be provided.
4.7
Tanker Loading Position- No Reversing Required
Safety
The position of tankers during loading shall be such that they can exit the plant without
reversing after loading.
© 2018 Air Products and Chemicals, Inc. All information herein is the property of Air Products unless another source is shown. This
document is classified as Air Products Internal Use Only, is subject to return on demand and must not be disclosed or reproduced
without prior written consent. This information may be subject to export controls. Disclosure contrary to U.S. law is prohibited.
Design Criteria for Plant Layout
3PI01001, Ошибка! Используйте вкладку "Главная" для применения Revision к тексту, который
должен здесь отображаться., Page 4 of 10
No.
Name
Category/
Reason Code
Safety
4.8
Main-gate Setback
Main-gate setback shall permit trucks to clear public roadways while waiting for gates to open.
Main gate setback shall be at least one trailer length according to selected trailer model.
Typically, this is 21 m (70 ft) for a liquid trailer.
4.9
Car Parking Location
4.9.1
Car parking shall be segregated from trailer parking and from operating areas. Also, separation
of truck and car traffic shall be considered when locating car parking areas.
4.9.2
Employee parking shall be separated from the plant production areas with a fence with
employees walking through an access control point.
4.10
Air Products Security
Safety
Safety
Review Global EH&S Standards 22-0008 “Perimeter Barriers” through 22-0015 “Facility Vehicle
and Pedestrian Entrances and Exits” for engineering related security standards. All Air Products
owned and operated plants shall comply with the global security standards.
Safety
4.11
Perimeter Fence or Barrier
4.12
According to EHS document 22-0008 “Perimeter Barriers”, the complete process plant, storage,
office, parking, vehicle maintenance area, vehicle refueling area, and truck scale shall be
surrounded by a chain link fence or other barrier.
The perimeter fence shall be a minimum of 2 m (8 ft) from the property line.
Safety
Main Access Gate Remote Operation
The main access shall have lockable gates that can be operated from a remote position. The
main gate shall be visible or capable of being monitored from its point of operation (for
example, a camera monitor located in the main control room).
4.13
Shipping and Receiving Points Near Perimeter
Safety
Shipping and receiving points shall be located near or on the perimeter, thereby limiting the
amount of non-Air Products traffic on the property and through process areas.
5.
OPTIONS FOR ENHANCEMENTS
No.
5.1
Name
In-line Layout
Category/
Reason Code
Operability
An in-line layout, in which equipment is arranged according to the process flow sequence,
should be used for air separation process equipment and large chemical plants to optimize
interconnection materials and to facilitate operation and maintenance.
5.2
Constructability
Similar Equipment Grouping Layout
A similar equipment grouping layout combines like equipment such as utilities, major process,
or compression equipment and storage. This approach should be used to minimize cost and
enhance operability, by combining platform, building, crane, and utility requirements.
© 2018 Air Products and Chemicals, Inc. All information herein is the property of Air Products unless another source is shown. This
document is classified as Air Products Internal Use Only, is subject to return on demand and must not be disclosed or reproduced
without prior written consent. This information may be subject to export controls. Disclosure contrary to U.S. law is prohibited.
Design Criteria for Plant Layout
3PI01001, Ошибка! Используйте вкладку "Главная" для применения Revision к тексту, который
должен здесь отображаться., Page 5 of 10
No.
5.3
Name
Functional-equipment Arrangement Layout
Category/
Reason Code
Operability
The functional-equipment arrangement consists of equipment with similar electrical or
hazardous classifications being grouped together.
5.4
Future Expansion Space
Constructability
Future expansion might require that adequate space is provided adjacent to some areas in the
plant. Cooling towers and storage areas can often be located to allow for future expansion at no
initial cost penalty.
5.5
Tower and Large Vessel Arrangement
Operability
Towers and large vessels should be arranged in rows with their centerlines on a common line, if
they are of similar diameters. If they are of differing diameters, they may be aligned to a
common face.
5.6
Maintainability
Heat Exchanger Maintenance Structure
Horizontal, shell-and-tube heat exchangers may be stacked. The centerline of the top heat
exchanger shall not exceed 4.0 m (12 ft) from grade without providing a permanent
maintenance structure.
5.7
Cooling Tower Alignment
Operability
Cooling towers up to 61.0 m (200 ft) long should be aligned parallel to the prevailing summer
wind, to minimize recirculation of the humid exhaust air. They should also be located away from
the plant boundaries and with a solid end wall toward the nearest boundary, since the low
frequency noise generated by a cooling tower is very difficult to attenuate and is directional.
5.8
Buildings near In-Plant Roads
Control, electrical, and analyzer buildings should be located near in-plant roads.
5.9
Compression Equipment Grouping
Operability
Constructability
When multiple units have similar building requirements, consideration should be given to
grouping and housing them in a single building. Grouping compression equipment can also
minimize electrical and cooling water runs, as well as allow sharing of deck or platform steel.
5.10
Product Storage and Trailer Loading
Efficiency
Product storage and trailer loading should be located in a common area. The location of product
pumps, transfer pumps, and pressure build-up (P.B.) coils should be immediately adjacent to
storage tanks.
5.11
Equipment Requiring Regular Maintenance
Maintainability
Large equipment that requires regular (once per year) maintenance should be accessible from a
floor or a permanent working platform. When this is not possible, adequate space should be left
for erecting scaffolding. Adequate space should also be provided when platforming is not
furnished for equipment maintenance that is required more often than once per year.
5.12
Equipment Requiring Dismantling or Replacement
Maintainability
Equipment that needs to be dismantled or replaced frequently (once every six months or more
frequently) should be positioned so that other equipment will not have to be disturbed. A clear
area for parts lay-down should be provided.
© 2018 Air Products and Chemicals, Inc. All information herein is the property of Air Products unless another source is shown. This
document is classified as Air Products Internal Use Only, is subject to return on demand and must not be disclosed or reproduced
without prior written consent. This information may be subject to export controls. Disclosure contrary to U.S. law is prohibited.
Design Criteria for Plant Layout
3PI01001, Ошибка! Используйте вкладку "Главная" для применения Revision к тексту, который
должен здесь отображаться., Page 6 of 10
No.
5.13
Name
Equipment Requiring Moving or Servicing
Category/
Reason Code
Maintainability
Heavy or large items of equipment that need to be moved from the plant for servicing should be
placed to facilitate crane access, loading onto transport vehicles, and reinstallation. If these
items are located in a building, crane access should be facilitated by removable roof panels.
5.14
Additional Space for Withdrawal of Serviceable Items
Maintainability
Space should be provided for withdrawal of such items such as heat exchanger tube bundles and
filter cartridges. See Table 2
Maintainability
5.15
Additional Space for Equipment Maintenance
See Table 2 for recommended equipment clearances.
5.16
Operability
Liquid Production Plant Truck Traffic Flow
For liquid production plants, a one-directional flow of truck traffic through the loading cycle is
recommended.
5.17
Garage and Vehicle Washing Facilities
Maintainability
Garages, when specified, should be located in the main traffic pattern on the primary road and
away from the process area. Vehicle washing facilities should be located near the garage and be
accessible to a sanitary sewer or process water disposal system.
5.18
Vehicle Refueling
Operability
Vehicle refueling should be located between the main gate and the truck scale. Installation must
provide for two-way traffic during refueling.
Efficiency
5.19
Load-on Scales for Liquid Producing Facilities
5.20
Load-on scales should be considered for liquid-producing facilities. Load-on scales with automatic
trailer filling allow tankers to fill the maximum allowable road weight and eliminate over or under
filling of trailers. Load-on scales reduce plant traffic and support one-directional traffic flow
through the facility, thereby providing a safer and quicker turnaround.
Operability
Single Truck Scale Location
Location for a single truck scale should be along the primary road between the fueling point and
the loading area.
5.21
Operability
Two-way Traffic on Truck Scale Installation
Truck scale installation should provide for two-way traffic with the scale occupied.
5.22
Weather Proofed Scale Readout
The scale readout should be housed indoors or be suitably weatherproofed.
Reliability
5.23
Scale Located to Prevent Vehicles Reversing or Turning
Operability
The scale should be located so that vehicles may drive onto and away from it without reversing
or turning and to avoid cross traffic.
© 2018 Air Products and Chemicals, Inc. All information herein is the property of Air Products unless another source is shown. This
document is classified as Air Products Internal Use Only, is subject to return on demand and must not be disclosed or reproduced
without prior written consent. This information may be subject to export controls. Disclosure contrary to U.S. law is prohibited.
Design Criteria for Plant Layout
3PI01001, Ошибка! Используйте вкладку "Главная" для применения Revision к тексту, который
должен здесь отображаться., Page 7 of 10
Table 1
Personnel and Equipment Safety Clearances
Length units, m (ft)
Horizontal Operating
Clearances, m (ft)
Minimum
Preferred
In structures
0.75 (2.5)
1.0 (3)
On vessels
0.75 (2.5)
1.0 (3)
Stairways
0.75 (2.5) width
1.0 (3)
Cooling Tower Stand Pipes
6 (20)
Access between wall and
process equipment
0.75 (2.5)
1.0 (3)
Horizontal Operating
Clearances, m (ft)
Front
(Minimum*)
Front
(Preferred)
Rear
(Minimum*)
Rear
(Preferred)
Based on
voltage. See
NFPA 70
2.0 (6)
0.762 (2’6”)
1.50 (4)
Main Control Panel
Switchgear-high voltage
(600 to 13,800 volts)
1.50 (5)
-
0.762 (2’6”)
0.9 (3)
Switchgear-low voltage
(up to 600 volts)
1.0 (3’ 6”)
1.25 (4)
0.762 (2’6”)
0.9 (3)
Motor starters: 2.3 kV
1.25 (4)
-
-
-
Motor Starters: 4.16 kV
1.25 (4)
1.50 (5)
-
-
480 volt motor control
centers
1.0 (3’ 6”)
-
-
Between Instrument
Racks
-
-
-
2.0 (6)
* Minimum clearances are based on NFPA 70 National Electrical Code (NEC) condition 2: Exposed live
parts on one side of the working space and grounded parts on the other side of the working space.
Energized parts on both sides (condition 3) will require additional clearances. For locations outside
the United States, clearances shall follow local electrical codes and regulations.
Vertical Overhead Clearances*, m (ft)
Minimum
Preferred
Passageways, walkways, platforms
1.8 (6)
2.30 (7.5)
Aisles, aisleways
2.30 (7.5)
Accessways
3.0 (10)
Secondary plant roads
4.1 (13.5)
Primary plant roads
5.5 (18.0)
Under main pipeways, pipe racks
6.0 (20)
3.0 (10)
Electric panels
2 (6.5)
Instrument panels
0.15 (0.5)
0.75 (2)
* as measured to the lowest point of member or line, including but not limited to, insulation, flanges,
fittings, and supports
© 2018 Air Products and Chemicals, Inc. All information herein is the property of Air Products unless another source is shown. This
document is classified as Air Products Internal Use Only, is subject to return on demand and must not be disclosed or reproduced
without prior written consent. This information may be subject to export controls. Disclosure contrary to U.S. law is prohibited.
Design Criteria for Plant Layout
3PI01001, Ошибка! Используйте вкладку "Главная" для применения Revision к тексту, который
должен здесь отображаться., Page 8 of 10
Table 2
Equipment Clearances
Length units, m (ft)
 Equipment Clearances
Note: Distances are based on large equipment
items. Judgment should be applied when
locating smaller items typically
encountered in air separation plants.
Tube bundle removal
Bundle length, plus 1.0 (3)
Piston rod removal
Rod length, plus 0.75 (2.5); 1.25 (4) side
clearance
Agitator shaft removal
Shaft length plus 1.25 (4) preferred (where
agitator is "top or bottom entering" within a
closed structure, an individual analysis shall be
made)
In front of exchanger channel and cover
ends
1.25 (4) outdoor; 0.75 (2.5) indoor
Access to pumps
1.0 (3) both sides preferred; 0.75 (2.5)
minimum
Access between pumps and wall
1.25 (4)
Access between two rows of pumps
2.0 (6) outdoor; 1.25 (4) indoor
Access around outside of ambient
vaporizer banks
0.75 (2.5), 2 (6) preferred
 Maintenance Equipment Clearances
10 to 20 U.S. ton loads
5.5 (18) minimum width, 4.25 (14) minimum
height, 7.3 (24), minimum length [ or 22’ x
22’]
21 to 100 U.S. ton loads
7.62 (25) minimum width, 4.25 (14) to 4.9
(16) minimum height (, 8.5 (24) minimum
length [Typical 100 ton crane have outrigger
spread of 25 wide x 28’ long.]
101 to 300 U.S. ton loads
9.1 (30) minimum width, 5.0 (16) to 5.50 (18)
minimum height, 9.1 (30) minimum length
[Typical 300 ton crane have outrigger spread of
30 wide x 30’ long.]
Note: Table 2 equipment clearances are only mandatory when options 5.14 and 5.15 are selected;
therefore, these are not mandatory.
© 2018 Air Products and Chemicals, Inc. All information herein is the property of Air Products unless another source is shown. This
document is classified as Air Products Internal Use Only, is subject to return on demand and must not be disclosed or reproduced
without prior written consent. This information may be subject to export controls. Disclosure contrary to U.S. law is prohibited.
Design Criteria for Plant Layout
3PI01001, Ошибка! Используйте вкладку "Главная" для применения Revision к тексту, который
должен здесь отображаться., Page 9 of 10
Table 3
Roads
(Road Classification)
Road
Characteristic
Primary
Secondary
Service
Maintenance
Other*
Vehicle type
2 or 3 axle,
heavy
2 axle, light
Any
Any
Heavy cranes
Application
Product/Raw
material
Service
Service
Maintenance
Construction
Number of lanes
2
2
1
1
Variable
Width, m (ft)
6 (20)***
5.0 (16)
4.0 (12)
4.0 (12)
Variable as
required by
Construction
Surface
All-weather
surface
All-weather
surface
All-weather
surface
Stone
Stone
Head room, m
(ft)**
5.5 (18)
4.5 (14)
4.5 (14)
4.5 (14)
As required
Inside radius, m
(ft)
15.0 (50)
7.5 (25)
---
---
---
Frequency of use
Daily
Daily
---
---
---
Notes:
*
When possible, roads shall be initially designed for other use.
**
Measured from the crown of the road.
***
A hard shoulder 1 m (3'-0") wide is required both sides of the roadway.
Table 3.Road requirements are mandatory for Air Products owned and operated plants only.
© 2018 Air Products and Chemicals, Inc. All information herein is the property of Air Products unless another source is shown. This
document is classified as Air Products Internal Use Only, is subject to return on demand and must not be disclosed or reproduced
without prior written consent. This information may be subject to export controls. Disclosure contrary to U.S. law is prohibited.
Design Criteria for Plant Layout
3PI01001, Ошибка! Используйте вкладку "Главная" для применения Revision к тексту, который
должен здесь отображаться., Page 10 of 10
6.
RELATED INFORMATION
6.1
Air Products Engineering Documents
3PI25010
Venting of Nontoxic and Nonflammable Substances
3PI25011
Venting of Buoyant Flammable Gases
3ES60101
Safety Distance Criteria for Air Separation Plants
3EL64550
Spacing Criteria for Oil-filled Transformers and Oil-filled AutoTransformers
3EQ93012
Minimum Requirements for Standard Bulk Gaseous Hydrogen
Customer Installations
3EQ12002
Requirements for Gaseous Hydrogen Tube Trailer Filling Locations
STD-ENG-ES012
Separation Distances for Storage Systems and Process Equipment
EP-9.1
Safety Review Plan
EP-9.3
Environmental Strategy
About this document (for Air Products Internal Use Only)
Version History (for Air Products Internal Use Only)
6.2
6.3
Global EH&S Standards:
25-010912
Siting and Design of Occupied Plant Buildings for Overpressure
Protection
22-0003
Air Products Chemicals of Concern List for Product Security
Management
22-0008
Perimeter Barriers
22-0009
Facility Internal Security Barriers
22-0010
Facility Closed-Circuit Television Systems
22-0011
Facility Intrusion Monitoring Systems
22-0012
Contracted Uniform Guard and other Protective Services
22-0013
Facility Security Lighting
22-0014
Facility Access Control Systems
22-0015
Facility Vehicle and Pedestrian Entrances and Exits
National Fire Protection Association (NFPA)
National Fire Code
© 2018 Air Products and Chemicals, Inc. All information herein is the property of Air Products unless another source is shown. This
document is classified as Air Products Internal Use Only, is subject to return on demand and must not be disclosed or reproduced
without prior written consent. This information may be subject to export controls. Disclosure contrary to U.S. law is prohibited.