Studbolt

A studbolt is a threaded rod with threads at both ends, often used to clamp two parts together with nuts. It is common in piping and pressure equipment where a through-bolt is not practical.

A studbolt joins two flanged or clamped parts through aligned holes. It takes two nuts, often with washers, and it is tightened from both ends. A duplex studbolt suits offshore, marine and process piping where resistance to chloride stress corrosion cracking is needed.

Studbolts of this kind are often made in super duplex stainless steel, which gives high strength and good resistance to chloride attack. The grade is usually supplied in a strain hardened or solution annealed condition, and the condition is matched to the service.

This is a general guide to checking this kind of part. It says nothing about any supplier's parts.

Ask for a mill test certificate or certificate of conformance for the studbolts. On receipt, check the grade marking, thread condition and surface finish against the order.