CPSystemBD. 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:

Water is trapped.

The paint system fails (atmospheric coatings soften in immersion service).

Corrosion is initiated.

Corrosion undercuts paint film.

Crevice corrosion starts.

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.