Instrumentation tubing clamps are often used in very arduous environments, where they are faced with severe environmental conditions and high temperatures. The correct specification of clamp is therefore vitally important as there are materials available which can withstand these harsh conditions.
High temperatures can cause an issue with some clamp designs as they are not manufactured specifically to withstand them. For example:
Polypropene is effective at maximum temperatures of 90oC
Polyamide can withstand a maximum temperature of 120oC
Thermoplastic elastomer - a temperature of 125oC.
For many applications in the oil and gas, petrochemical and industrial sectors, these clamps would not be sufficiently robust.
The obvious choice is metal clamps. And, in some cases aluminium is used, which operates effectively up to temperatures of 300oC but it does have the risk of galvanic corrosion when used in combination with other materials.
The Norwegian offshore standard NORSOK Z-CR 010 states that instrumentation tubing clamps shall be made of non-corrosive material, stainless steel AISI 316 or flame resistant plastic. However, our experience in the oil and gas industry and extensive investment in R&D has led us to conclude that in most cases only 6Mo material will do. Super austenitic stainless steel 6Mo is a high-performance alloy designed specifically for providing corrosion and heat resistance. 6Mo is renowned as a material that has an extremely high-temperature tolerance, making it suitable for a wider range of upstream and downstream applications. It is often used as a replacement in critical components where alloy 316/316L has failed or is considered unsuitable.
Instrumentation clamping can be exposed to extremely high temperatures either via the temperature of the internal media or externally, as in a recent project that Parker supplied. Working through an EPC contractor, Parker recommended the instrumentation clamp Snap-Trap®+, manufactured from 6Mo, to a cement works in Spain. The tubing lines were manufactured from 316 Stainless Steel and passed very close to the hot kiln, where temperatures were in excess of 500oC. Parker’s Snap-Trap®+ clamping system was specified as it is capable of withstanding these high temperatures and could effectively hold the tubing lines in place without risk of deterioration of the clamps.
Snap-Trap®+ is also very quick and easy to install and requires no nuts or spanners – just a simple tool working on a lever principle ensures correct installation quickly. This can help to reduce installation costs and allow productivity to begin earlier.
So, when it comes to instrumentation tube clamps for offshore or other hazardous environments, specifying 6Mo is essential. Opting for toughened plastic, or even 316 Stainless Steel, can lead to issues with inability to withstand high temperatures or corrosion. Use of 6Mo clamps and tubing avoids these issues and therefore extends asset life and improves levels of safety in critical operations.
Jim Breeze is Product Manager, Instrumentation Connections and Process Valves, Parker Hannifin, Instrumentation Products Division, Europe.