There are many reasons why bolts should be included in the material specification, particularly in the oil & gas and petrochemical industry. In this latest blog from the Process Control team, we present an overview of items for consideration that may not always be considered for a commodity part.
Because the high chloride environments where the instrumentation is used, including seawater and bleach plants, are extremely corrosive, it is a good idea if Corrosion Resistant Alloys (CRA) are specified by engineers for all parts in these applications. Super austenitic stainless steel 6Mo is a high-performance alloy renowned for its corrosion resistant properties.
It can be a false economy if inferior materials are chosen for the bolts, rather than corrosion resistant alloys. In highly exposed environments, 6Mo is often specified by engineers for instrumentation systems, including tubing, manifold, gauge, and fittings. However, bolts may seem like the last piece of the jigsaw - a tiny part of an overall system - but if the wrong material is specified, this could lead to the whole system’s downfall. Corrosion of the bolts in a hook up could lead to stress corrosion and cracking, causing them to snap, which results in catastrophic failure and the potential for accident and injury.
The third reason is that inferior material specification can cause maintenance issues too. Corrosion to the bolts can be so rapid that by the time it is noticed, the bolts simply cannot be replaced. Instead, they have to be sawn off, potentially causing expensive damage to the instrument tubing system.
Similarly, if tubing clamps are not manufactured from corrosion resistant alloys, this could lead to stress cracking and fatigue, resulting in equipment failure.
Specifying a Corrosion Resistant Alloy, such as 6Mo, throughout the instrumentation tubing system, including all component parts, gives complete peace of mind. Specifiers and customers can, therefore, be reassured that all components, including bolts, will ensure the durability and long-term performance of their instrumentation system.
Deborah Pollard is business development leader capital projects, Instrumentation Products Division, Europe of Parker Hannifin.