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.

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

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

		I-Rod (White)		I-Rod HT (Amber)		PEEK (Tan)
Property value	ASTM Test	Metric	Imperial	Metric	Imperial	Metric	Imperial
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

Polyolefin (heat shrink) specifications

U-Bolt weights and load values

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)

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

Nu-Bolt Pipe Bolt Dimensions

There are 2 accessories for the Nu-Blot & I-Rod Pipe Supports: the I-Rod Adhesive and the I-Rod Clip. Details for each accesory can be found below.

I-Rod Adhesive   I-Rod® Adhesive™ provides a strong, permanent bond between I-Rod® strips and pipe supports I-Rod® Adhesive™ is designed to securely anchor strips of I-Rod® in situations where drilling and bolting would be difficult. It’s a great solution for using I-Rod® on solid concrete supports that can’t be fitted with U-bolts, or for locations where drilling through metal is restricted or would require a hot work permit. Cartridge Coverage

I-Rod Clip

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.