What is welded bellows and seamless bellows ?

1. WELDED BELLOWS:

We can find lots of welded bellows in the market. They are mostly make of welded stainless steel pipes. Very normal and popular. Considering leakage problem, Usually using 2 ply to make bellow. Or even Muti-ply to make bellows. Regular material will be stainless steel. 316L,321,304 etc. Usually thickness of single ply is from 0.15mm~0.6mm.

Advantage: can make large diameter bellows. Multi-ply can use under high pressure and high temperature condition. Will be less expensive than seamless bellows. For industrial line mostly

Disadvantage: Considering multi-ply,the Flexibility will be worse than seamless bellow which is using as spring unit.

2.SEAMLESS BELLOWS:

Made from seamless tubes . seamless tubes are made with hydraulically or mechanically roll-formed compressed,Then will use the same manufacturing method as welded bellows. Bellow-forming the seamless tubes.Regular material are : stainless steel,brass beryllium copper, phosphor bronze, and even alloy like Monel, Inconel etc.Usually thickness of single ply is from 0.1mm~0.3mm.

Advantage: can make very small diameter bellows. Good spring rate can make it for long life using without leakage problem . can be using for Valve, pressure meter ,flow meter and semi-conductive field etc.

Disadvantage: quite expensive,high requirement on material treatment in order to make seamless tube.