TWI Industrial Member Report Summary 657/1998
A M Barnes
The modified 9%Cr1%Mo steel (ASTM A387 grade 91) offers good elevated temperature properties, oxidation resistance and resistance to hot hydrogen attack. It is finding increasing application within the power industry, both for the construction of new plant and the upgrade of existing plant, in, for example, heat exchange tubing and headers. Other industrial sectors, although acknowledging the favourable properties offered by this grade, have yet widely to adopt its use.
It is essential with such steels that good weldment creep properties can be achieved, but adequate toughness is also required to avoid problems during pressure testing and start-up/shut-down. It is acknowledged that current commercial consumable formulations may not be optimised in relation to toughness.