NEW TRENDS IN
PIPING SYSTEMS
Robert A. Maffei, P.E.
Vice President of Sales & Marketing
PERMA-PIPE, Inc.
Low Temperature Products
Polyurethane
insulation
-320F to 250F
-200C to 120C
Choice of jacket
materials
Materials
™Service pipe: Steel, FRP, HDPE,
Ductile Iron, PVC
™Insulation: Polyurethane, density, thickness
™Insulation Jacket: FRP, PVC, HDPE
Steel Pipe
Advantages:
Durable and ideal for higher pressure applications
™ Welded construction- Contractors are familiar with steel
welding and layout techniques and procedures
™ Welded joint quality can be verified with a variety of NDE
methods (x-ray, ultrasonic, magnetic particle
™
Disadvantages:
OD Corrosion - must be installed dry and kept dry.
™ ID Corrosion - water must be treated
™ Relatively expensive
™
FRP Pipe
Advantages:
™ Non-corrosive
in most environments
™ Light weight, easy to handle
™ Fitting pressure rating same as the straight pipe
Disadvantages:
™ Field
joints difficult to make in hot or cold
environments and for larger pipe sizes
™ Limited NDE methods to verify field joint quality
™ Expensive in larger pipe sizes
HDPE Pipe
Advantages:
Excellent ID/OD corrosion resistance
™ Relatively lower costs
™ Butt Fusion (done properly) can achieve the same rating
as the pipe
™ Lighter than steel but heavier than FRP
™
HDPE Pipe
Disadvantages:
Limited pressure ratings (SDR7 = 267 PSI, SDR9 =
200 PSI, SDR11 = 160 PSI, SDR17 = 100 PSI)
™ Large pipe sizes have very heavy wall thickness
24 inch SDR9 wall thickness = 2.67 inches.
™ Mitered fittings (elbows and tees) must be de-rated
from the straight pipe pressure rating (must use higher
SDR for fitting pipe)
™ Cold weld, bad joint preparation can cause joint failure
™ Limited NDE methods to verify field joint quality
™
Ductile Iron Pipe
Advantages:
Durable and suitable for higher pressure applications
™ Simple installation techniques and procedures
™ Restrained joints or thrust blocks
™ Relatively corrosion resistant
™
Disadvantages:
Gasketed bell & spigot joints can leak
(allowable leakage in AWWA standards)
™ Very heavy in larger pipe sizes, difficult to handle
™ Fairly expensive
™
PVC Pipe
Advantages:
Light weight and easy to handle
™ Simple installation techniques and procedures
™ Restrained joints or thrust blocks
™ Corrosion resistant
™
Disadvantages:
Gasketed bell & spigot joints can leak
(allowable leakage in AWWA standards)
™ Low strength and brittle in cold temperatures
™ Fairly expensive in large pipe sizes
™
FRP Jacket
Advantages:
High strength and impact resistance
™ Can be filament wound directly onto polyurethane
foam
™ Relatively high temperature
™
Disadvantages:
™
High Cost
PVC Jacket
Advantages:
™
Low cost
Disadvantages:
Low strength and impact resistance
™ Brittle at low installation temperatures
™ Can not be easily welded
™
HDPE Jacket
Advantages:
™
Combination of strength, flexibility and toughness
Can be butt fusion or extrusion welded
Can be extruded directly onto polyurethane foam
Fairly low cost
™
Disadvantages:
™
Difficult to bond to polyurethane foam
Relatively low temperature resistance
™
™
™
™
Polyurethane
¾ An Engineered Material
¾ Compressive Strength vs. Density
¾ Thermal Conductivity vs. Density
¾ Thermal Conductivity vs. Temperature
Polyurethane Thermal Conductivity
Insulation
Thermal Cond. @ 74 OF 23 OC
(Btu in./hr. ft.2 OF)
( W/m- OC)
2 lb./ft.3
32 Kg/m.3
0.16
.023
4 lb./ft.3
64 Kg/m.3
0.18
.026
6 lb./ft.3
96 Kg/m.3
0.19
.027
0.29
.042
Cellular glass
Polyurethane insulation thermal conductivity increases at higher temperatures.
¾ Superior polyurethane thermal conductivity results in reduced insulation thickness
and cross section size for equivalent thermal design.
¾
Thermal Conductivity vs. Density
Thermal Conductivity (BTU-in/hr-ft2-oF)
0.24
0.20
0.16
0.12
0
2
4
6
8
Density (lbs/ft3)
10
Thermal
Conductivity
vs.
Temperature
Polyurethane Compressive Strength
Insulation
2 lb./ft3 32 Kg./m3
polyurethane
4 lb./ft.3 64 Kg./m3
polyurethane
6 lb./ft.3 96 Kg./m3
polyurethane
Cellular glass
Minimum Compressive Strength
(psi)
(kPa)
30
207
60
414
90
620
87
600
Compressive Strength vs. Density
1000
900
800
700
600
500
400
COMPRESSIVE STRENGTH AT 10% DEFLECTION (PS
300
200
100
90
80
70
60
50
40
Uppe r Ra nge of
Compre ssive Stre ngth
30
20
Low e r Ra nge of
Compre ssive Stre ngth
10
1
2
3
FOAM DENSITY (LB/FT3)
4
5
6
7
8
9
10
Spray Applied vs. Injection
Injected PU foam
Sprayed PU foam
z
z
z
z
z
z
z
z
z
No insulation voids
Fully concentric
Jacket fully bonded to the insulation
Consistent density
Consistent compressive strength
Consistent thermal conductivity
Precise thickness
Lower cost
Easy inspection / higher quality
z
z
z
z
z
z
z
z
z
May have voids
Not concentric
Jacket may not bond to
insulation
Inconsistent density
Inconsistent compressive strength
Inconsistent thermal conductivity
Predetermined thickness increments
Higher cost
Difficult inspection / lower quality
Cell Structure
Spray Applied
Uniform Cell Structure.
Injected
Compressed Cell Structure.
Structure
Injected Foam
Non concentric
service pipe
Insulation shrinkage and
separation from jacket
Voids in Injected Insulation
Importance of Void Free Insulation
(Cryogenic Service)
Loss of Insulation at Void Site
Increased Heat Gain
Ice Build-up
Spray Foam
Polyurethane Foam
Blowing Agents
CFC R-11 (Freon) No longer used
™ HCFC R-141b No longer used
™ HFC 245fa Used in USA
™ HFC 365mfc Used in Europe
™ Cyclopentane Used in USA and Europe
™ CO2 (Water blown Foam)
™ Air (Not a blowing agent)
™
K Value
.061
.069
.085
.074
.083
.110
.186
Factory Pre-insulated Piping
™
Manufactured under factory controlled conditions
with process and product control
™
High quality, seamless insulation and jacket
™
Insulation bonded to service pipe and jacket
™
Economical insulation and jacket system
Quality Assurance Considerations
Certified mill test reports for pressure pipe and pipe fittings for
mechanical and physical properties
™ In Processing Insulation Testing
™ Thermal conductivity
™ Compressive strength
™ Density
™ Closed cell content
™ In Process Insulation Jacket Testing
™ Tensile strength
™ Elongation
™ Hardness
™ Bonding strength to insulation
™ Service Pipe welding and inspection in accordance with
appropriate ASME B31 piping code
™
XTRU-THERM Straight
HDPE Wind-Down End Seal
XTRU-THERM Straight
Test samples are placed in
Testing chamber
Test pressure is 11 PSI 76 kPa
(red fluorescent dye in water)
Removing wind down end seal
No evidence of water ingression
Removing shrink end cap
No evidence of water ingression
XTRU-THERM Elbow
Preinsulated Elbow Fittings
™Molded HDPE Jacket
™No welds or seems
™High quality
™Lower costs
™Ease of fabrication