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Nu-Bolt & I-Rod Pipe Supports by Deepwater

Eliminate corrosion problems at pipe supports with the Nu-Bolt and I-Rod dielectric pipe support system by Deepwater.

Nu-Bolt & I-Rod Pipe Supports by Deepwater

The Problem

Corrosion at pipe supports is one of the leading causes of process piping failures. It is the beam supports and saddle clamps that have historically caused the majority of problems. These have the following undesirable features in common:

  • Crevices – the formation of a crevice at the pipe surface.
  • Water Entrapment – water is trapped and held in contact with the pipe surface.
  • Poor Inspectability and Maintainability – virtually impossible to paint or otherwise maintain; visual and/or NDT inspection are often difficult.
  • Galvanic Couples – even when both the pipe and support are steel, the metallurgical differences can still provide enough potential difference to drive a corrosion cell.


The Corrosion Mechanism:

  1. Water is trapped.
  2. The paint system fails (atmospheric coatings soften in immersion service).
  3. Corrosion is initiated.
  4. Corrosion undercuts paint film.
  5. Crevice corrosion starts.
  6. Pipe fails.

The Solution

Nu-Bolt™ and I-Rod® have been specified on thousands of offshore production platforms since 1987. They simply and economically address the root cause of crevice corrosion by:

  • Eliminating crevices.
  • Eliminating water entrapment.
  • Eliminating metal-to-metal contact.
  • Allowing for ease of inspection and maintenance.
  • Providing complete support to the piping system.

Nu-Bolt™

Designed by corrosion engineers, the Nu-Bolt assembly combines the half-round I-Rod support with a modified pipe U-bolt. A variety of corrosion-resistant treatments provide reliable, long-term service in the harsh operating environments associated with offshore oil and gas production and coastal process facilities.

Polyshrink is applied over the shank of the Nu-Bolt to protect the paint system during installation. Polyshrink is not designed to protect the Nu-Bolt. The material is a cross linked, high-compressive-strength, UV-stable polyolefin. It can remain in service in temperatures up to 230 °F (110 °C).

Coatings - The Nu-Bolt is available in 316 SS or carbon steel with one of two coatings: Hot-dip galvanized or SermaGard®. SermaGard is a corrosion-resistant coating reliable in even the harshest offshore conditions.

Half-round I-Rod support - The standard I-Rod material works extremely well for most process piping conditions. In situations with extreme operating temperatures, Deepwater can substitute the more resistant I-Rod HT material.

 

I-Rod®

I-Rod® is a high-strength thermoplastic rod in a half round configuration. I-Rod is inserted so the round surface interfaces with the pipe.

The half round profile:

  • Minimizes contact crevice, and thus eliminates moisture retention.
  • Provides a standoff between the pipe and support, and thus:
    - Insulates electrically.
    - Improves maintainability.
    - Improves inspectability.

The high-strength thermoplastic material also:

  • Provides excellent compressive strength.
  • Is UV stable.
  • Has a low friction coefficient, which assists in pipe fitting when used as a beam dressing, and reduces coating damage during new construction.

When used independently as a beam dressing, I-Rod® is typically supplied in 5’ and 10’ lengths.

Key design points

Half-round shape

The I-Rod's half-round shape minimizes contact between the pipe and the support, eliminating the crevice. Keeping water out minimizes corrosion.

Maintenance

The Nu-Bolt assembly provides an electrically isolated stand-off between the pipe and the supporting beam or saddle clamp. This allows for easy maintenance and inspection, while preventing galvanic corrosion between dissimilar metals (the pipe and support).

Durability

I-Rod also has excellent compressive strength and a very low friction coefficient. Nu-Bolt assemblies have been in continuous operation since 1989 with no reported failures.

Specifications

Below are the basic specifications for the Nu-Bolt Assembly, including the dimensions of the entire assembly (imperial and metric), I-Rod and I-Rod HT specifications, as well as specs for the polyolefin (heat-shrink) used to coat the U-bolt. Deepwater also offers PEEK material for environments that prove too severe for either (though these instances are rather rare). For information on PEEK or specifications for any other aspect of Deepwater's pipe support systems, please contact us.

Note: The information given herein is believed to be reliable. However, no guarantee or warranty of any kind is implied with respect to accuracy or completeness of these data.

 

Nu-Bolt pipe bolt dimensions

Nominal pipe sizeBolt stock ؔU-Bolt height
A
Thread length
B
Inside gap
C
Leg center
D
in mm in mm in mm in mm in mm in mm
1/2" 15 1/4" 6 3-1/4 83 2-3/8 60 15/16 24 1-3/16 31
3/4" 20 3-5/16 85 2-3/8 60 1-1/8 29 1-3/8 35
1” 25 3-7/16 87 2-3/8 60 1-3/8 35 1-5/8 41
3/8” 10 3-7/16 87 2-3/8 60 1-3/8 35 1-3/4 44
1-1/4" 32 3-3/4 95 2-1/2 64 1-11/16 43 2-1/8 54
1-1/2” 40 4 102 2-1/2 64 2 51 2-3/8 60
2” 50 4.5 114 2-1/2 64 2-7/16 62 2-13/16 71
2-1/2" 65 1/2” 13 5-1/4 134 3 76 2-15/16 75 3-7/16 87
3” 80 5-13/16 148 3 76 3-9/16 90 4-1/16 103

4"

100 6-13/16 173 3 76 4-9/16 116 5-1/16 129
5" 120 7-13/16 198 3 76 5-5/8 143 6-1/8 156
6" 150 5/8” 16 9-1/2 241 3-3/4 95 6-3/4 171 7-3/8 187
8" 200 11-1/2 292 3-3/4 95 8-3/4 222 9-3/8 238
10" 250 3/4” 19 13-13/16 351 4 102 10-7/8 279 11-5/8 295
12" 300 7/8” 22 16-1/16 408 4-1/4 108 12-7/8 327 13-3/4 349
14" 350 17-5/16 440 4-1/4 108 14-1/8 359 15 381
16" 400 19-5/16 490 4-1/4 108 16-1/8 410 17 432
18" 450 1” 25 21-11/16 551 4-3/4 121 18-1/8 461 19-1/8 486
20" 500 23-11/16 602 4-3/4 121 20-1/8 511 21-1/8 537
24" 600 27-11/16 703 4-3/4 121 24-1/8 613 25-1/8 638
28" 700 31-11/16 805 4-3/4 121 28-1/8 715 29-1/8 740
30" 750 33-11/16 856 4-3/4 121 30-1/8 765 31-1/8 791
36" 900 39-11/16 1008 4-3/4 121 36-1/8 918 37-1/8 943

 

Nominal pipe sizeBolt stock ؔI-Rod length
E
I-ROD hole Ø
F

I-ROD size
G

I-ROD height
H
in mm in mm in mm in mm in mm in mm
1/2" 15 1/4" 6 2-1/2 64 3/8 10 3/4 19 5/16 8
3/4" 20 3 76 3/8 10 3/4 19 5/16 8
1” 25 3 76 3/8 10 3/4 19 5/16 8
3/8” 10 3 76 1/2 13 1 25 7/16 11
1-1/4" 32 3-1/2 89 1/2 13 1 25 7/16 11
1-1/2” 40 4 102 1/2 13 1 25 7/16 11
2” 50 4-1/2 114 1/2 13 1 25 7/16 11
2-1/2" 65 1/2” 13 5 127 5/8 16 1 25 7/16 11
3” 80 6 152 5/8 16 1257/16 11

4"

100 7 178 5/8 16 1257/16 11
5" 120 8 203 5/8 16 1 25 7/16 11
6" 150 5/8” 16 9 229 11/16 18 1 25 7/16 11
8" 200 11 279 11/16 18 1 25 7/16 11
10" 250 3/4” 19 13-1/2 343 7/8 22 1-1/2 38 11/16 18
12" 300 7/8” 22 16 406 1 25 1-1/2 38 11/16 18
14" 350 17 432 1 25 1-1/2 38 11/16 18
16" 400 19 483 1 25 1-1/2 38 11/16 18
18" 450 1” 25 21-1/2 546 1-1/8 29 1-1/2 38 11/16 18
20" 500 23-1/2 597 1-1/8 29 1-1/2 38 11/16 18
24" 600 27-1/2 699 1-1/8 29 1-1/2 38 11/16 18
28" 700 31-1/2 800 1-1/8 29 1-1/2 38 11/16 18
30" 750 33.5 851 1-1/8 29 1-1/2 38 11/16 18
36" 900 39.5 1003 1-1/8 29 1-1/2 38 11/16 18

 

 

I-Rod, I-Rod HT and PEEK full material specifications

    I-Rod (White)
I-Rod Thermoplastic
I-Rod HT (Amber)
I-Rod HT
PEEK (Tan)
PEEK
Property valueASTM TestMetricImperialMetricImperialMetricImperial
Density, 73º F (23º C) D792 1.41 g/cm3 0.0509 lb/in3 1.28 g/cc 0.0462 lb/in3 1.31 g/cm3 0.047 lb/in3
Tensile strength, 73º F (23º C) D638 64.8 MPa 9,400 psi 114 MPa 16,500 psi 110 MPa 16 ksi
Tensile modulus of elasticity,
73º F (23ºC)
D638 2.62 GPa 380 ksi 3.45 GPa 500 ksi 3.44 GPa 500 ksi
Elongation (at break), 
73º F (23ºC)
D638 30-60% 30-60% 30-60% 30-60% 20% 20%
Flexural modulus of elasticity, 
73º F (23ºC)
D790 2.76 GPa 400 ksi 3.45 GPa 500 ksi 6.89 GPa 1000 ksi
Flexural strength, 73º F (23ºC) D790 82.7 MPa 13 ksi 138 MPa 20 ksi 172 MPa 25 ksi
Compressive strength, 10% def, 
73º F (23ºC)
D695 103 MPa 15 ksi 152 MPa 22 ksi 137 MPa 20 ksi
Coefficient of friction (dry vs steel) N/A QTM 55007 0.25 0.25 0.42 0.42 0.40 0.40
IZOD Impact (notched), 73º F (23ºC) D256 .534 J/cm 1 ft-lb/in of notch .267 J/cm 0.5 ft-lb/in of notch .534 J/cm 1.0 ft-lb/in of notch
Hardness, Rockwell, 
73º F (23ºC) M/R
D785 88/120 88/120 112/125 112/125 100/126 M103
Maximum service temperature (Long Term) 83 ºC 181ºF 171º C 340º F 249 ºC 480 ºF
Deformation under load D621 1.0% 1.0% - - - -
Melting point D3418 168º C 329º F 210º C 410º F 340 º C 644 º F
Coefficient of linear expansion E831 97.2 µm/m/ºC 54 µin/in/ºF 55.8 µm/m/ºC 31 µin/in/ºF - -
Heat deflection temperature, 
264 psi
D648 104 ºC 220ºF 204 ºC 400ºF 160 ºC 320 ºF
Flammability rating VL94 HB HB V-0 V-0 V--0 V--0
Dielectric strength, short term D149 16.5 kV/mm 420 V/mil 32.7 kV/mm 830 V/mil 18.9 kV/mm 480 V/mil-

 


I-Rod (cut and drilled) dimensions

Pipe
dia.
(in)
# of
cuts (per 10')
A. Rod length
(in)
B . Hole diameter
(in)
C. Hole center to center
(in)
D. Rod height (in)E. Rod width (in)
1/2 46 2.5 0.375 1.1875 0.313 0.75
3/4 38 3.0 0.375 1.375 0.313 0.75
1 38 3.0 0.375 1.625 0.313 0.75
1 34 3.0 0.5 1.75 0.438 1.0
1.5 29 4.0 0.5 2.375 0.438 1.0
2 26 4.5 0.5 2.8125 0.438 1.0
3 20 6.0 0.625 4.0625 0.438 1.0
4 17 7.0 0.625 5.0625 0.438 1.0
5 15 8.0 0.625 6.125 0.438 1.0
6 13 9.0 0.75 7.375 0.438 1.0
8 11 11.0 0.75 9.375 0.438 1.0
10 8.0 13.5 0.875 11.625 0.688 1.5
12 7.0 16.0 1.0 13.75 0.688 1.5
14 7.0 17.0 1.0 15 0.688 1.5
16 6.0 19.0 1.0 17 0.688 1.5
18 5.0 21.5 1.125 19.125 0.688 1.5
20 5.0 23.5 1.125 21.125 0.688 1.5
24 4.0 27.5 1.125 25.125 0.688 1.5
28 3.0 31.5 1.125 29.125 0.688 1.5
30 3.0 33.5 1.125 31.125 0.688 1.5
36 3.0 39.5 1.125 37.125 0.688 1.5

 

 

Polyolefin (heat shrink) specifications

Property valueASTM testMetricImperial
Max continuous operating temp   110 °C 230 °F
Min continuous operating temp   -55 °C -67 °F
Tensile strength D412 ISO 37 14.47 MPa 2,100 psi
Elongation D412 ISO 37 550% 550%
Longitudinal change D2671 +1%, -10% +1%, -10%
Specific gravity D792 ISO/R1183 1.1 1.1
Elongation after heat aging (168 hrs @ 150º C) D2671 ISO 37 500% 500%
Heat shock (4 hrs @ 225º C) D2671 No cracking /flowing No cracking /flowing
Low-temperature flexibility (4 hrs @ -55º C) D2671 No cracking No cracking
Hardness D2240 50D 50D
Dielectric strength D149 IEC 243 500 KV/mm 12,700 volts/mil
Dielectric voltage withstand (2500V, 6-Hz, 1 min) UL 486D No breakdown No breakdown
Volume resistivity D257 1016 Ohm/cm 1016 Ohm/cm
Fluid resistance MIL-DTL 23053/5, ISO 1817 ISO 37 Good to excellent Good to excellent
Copper corrosion D2671 No corrosion No corrosion
Water absorption D570 0.1% 0.1%
Fungus resistance G21 No growth No growth
Adhesive softening point E28 92 +/- 5 °C 197 +/- 10 ºF
Adhesive peel strength (300mm/min @ 23º C) D1000 - -
-to steel, alum, P.E. D1000 61 N/cm 35 pli
-to PVC D1000 35 N/cm 20 pli
Adhesive lap shear (1 in / min at 23º C) D1002 mod 0.86 MPa 125 psi
Adhesive blocking (30º C) D1146 No blocking No blocking
Water penetration STM 706 No penetration after 286 hrs minimum of cont. immersion

 


U-Bolt weights and load values

Nominal pipe sizeBolt stock Ø”Max recommended load @ 650ºFMax recommended load @ 750ºFApproximate weight with nuts
(does not include I-Rod)
in mm in mm lbs. kg lbs. kg lbs. kg
1/2" 15 1/4" 6 485 220 435 195 0.11 0.05
3/4" 20 0.12 0.06
1” 25 0.06
3/8” 10 1220 550 1090 495 0.28 0.13
1-1/4" 32 0.30 0.14
1-1/2” 40 0.33 0,15
2” 50 0.73 0.33
2-1/2" 65 1/2” 13 2260 1025 2020 915 0.78 0.35
3” 80 0.84 0.38

4"

100 0.90 0.41
5" 120 1.00 0.45
6" 150 5/8” 16 3620 1645 3230 1465 2.00 0.90
8" 200 2.30 1.04
10" 250 3/4” 19 5420 2460 4830 2195 4.90 2.23
12" 300 7/8” 22 7540 3425 673 3050 7.70 3.50
14" 350 8.30 3.77
16" 400 9.20 4.18
18" 450 1” 25 9920 4500 8850 4020 13.5 6.14
20" 500 14.6 6.63
24" 600 16.9 7.68
28" 700 18.0 8.18
30" 750 19.1 8.68
36" 900 23.2 10.54

 

 

I-Rod load values (when using I-Rod as a beam dressing)

Piping engineers: Use the following maximum loading for each I-Rod. Up to three rods can be used to achieve desired weight loading:

1 in I-Rod 8,000 lb (3636 Kg)    1 ½ in I-Rod 10,000 lb (4545 Kg)

The table below conservatively estimates total weight/foot of pipe filled with water. Multiply this number by support spacing to get total weight loading, then select number of 1 in. I-Rods if pipe is less than 12 in. 1 ½ in. I-Rods are generally recommended for piping over 12 in. Do not mix rod sizes. 

 

Weight (lb) / foot of piping full of water (conservative)

Nominal
pipe
size (in)
Outside
diameter (in)
StdSch 40X-StrongSch 80Sch 120Sch 140Sch 160XX
Strong
2 2.375 6 6 7 7     9 11
3 3.500 12 12 14 14     18 23
4 4.500 18 18 22 22 26   29 34
6 6.625 33 34 44 44 51   60 68
8 8.625 51 54 69 69 86 93 100 98
10 10.750 76 80 94 104 129 143 155 143
12 12.750 104 110 121 144 181 195 215 181
14 14.000 122 131 140 173 217 237 255  
16 16.000 151 171 171 224 280 310 332  
18 18.000 183 216 205 282 354 384 418  
20 20.000 217 261 242 346 432 447 514  
24 24.000 294 370 325 494 625 678 737  
26 26.000 337   370          
28 28.000 383   419          
30 30.000 431   470          
36 36.000 593 731 639          
42 42.000 780   834          

 

I-Rod material health hazard data (standard I-Rod material only)

Acute or immediate effects: Routes of entry and systems
INGESTION: Not a probable route of exposure
SKIN: Molten I-Rod® causes thermal burns
EYE: Mechanical irritation only
INHALATION: Shapes not respirable


Emergency first aid

• If exposed to fumes from overheating, move to fresh air. Consult a physician if symptoms persist
• Wash skin with soap and plenty of water •Flush eyes with water. Consult a physician if symptoms persist 7•If molten I-Rod contacts skin, cool rapidly with cold water. Do not attempt to peel I-Rod from skin. Obtain medical attention to thermal burn.

Chronic effects: Chronic inhalation studies in animals have shown that Formaldehyde causes cancer in rats. The international agency for re

Nu-Bolt Pipe Bolt Dimensions


Questions & Answers

To assist our customers, we have put together answers to the most frequently asked questions regarding I-Rod pipe support systems.

Q:   “Is I-ROD made of Teflon?”
A: No, I-Rod is a high-impact thermoplastic material. Teflon would not function due to lack of compressive strength.
Q: “Is the material on a Nu-Bolt Neoprene?”
A: No, it is a cross-linked, heat-shrinkable polyolefin material. Neoprene would have to be vulcanized to stick to the U-Bolt, and would deform too much, and cause problems with moisture.
Q: “What is the maximum piping temperature that I can use I-Rod on?”
A: Normally, at temperatures above 90°C (194°F) crevice corrosion is not a problem, because the water simply evaporates. This is therefore our upper recommended continuous service temperature. The material will, however, perform up to 120°C (250°F), but may experience some slight deformation at the contact area.
Q: “Does the I-Rod create a stress raising point on the pipe?”
A: No, not if the piping is correctly supported along it’s length. If there is noticeable sagging between support points then the pipe is being overstressed, and inadequately supported. Note: I-Rod has been used on hundreds of thousands of pipe supports since 1987 and we have never seen a problem.
Q: “How do I know I’m buying I-Rod and not some inferior copy?”
A: Every shipment of I-Rod is traceable, and is sent with a certificate of authenticity. I-Rod is distinctly marked as such.
A Case Study of 13 Years of Offshore Exposure

The photos below were recorded during a routine topside inspection of an offshore structure that was installed in 1989. This was the first offshore structure where the I-Rod system was specified for new construction. The total added cost of this system was less than $10,000. The photos demonstrate the success of the system, which has subsequently been used on thousands of offshore structures.

Installed Nu Bolts - No crevice corrosion. Fuel gas line, always wet. Green coloration is mold. The beam paint system has failed, but there is not corrosion at pipe support.
I-Rod installed under pig launch/receive barrel, bolted to support beams. I-Rod was found particularly effective on small diameter, screwed piping, which typically has the highest maintenance cost per square foot.
 
I-Rod were also found effective on the largest diameter piping of the offshore structure.  
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