Killed Carbon Steel

Killed carbon steel refers to steel during whose manufacture all oxygen dissolved in the metal is removed by de-oxidizers so that the metal is sound. Rimmed steel is one in which no such procedure to ensure the oxygen removal is followed. The use of this type of steel for Steam service is better but it must have the required wall thickness calculated by design. No chemical reaction will take place through steam. We use killed steel for low temp. service due to its higher impact strength at lower temperatures as compared to ordinary steel.

If you are talking about piping, A-106 Gr.B or API-5L Gr. B seamless quality of piping along with corresponding fittings, flanges, etc. are suitable for the above steam service. If the temp. exceeds 420 deg. C it is necessary to use low alloy steels such as C-1/2 Moly and for still higher temp. such as above 450 deg. C, 1Cr-1/2 Moly.

Banu....

Based on your question, I assume that you have little experience with power piping design.

High pressure steam systems must be specified, designed, repaired and inspected to nationally recognized codes. Specification of piping materials must be done by experienced engineers in accordance with these codes and standards.

HP steam systems are often specified to be fabricated from "fully-killed" steels, made via fine grain practice, that are acceptable and in accordance with the piping code.

Because the failure of HP steam piping can be deadly, this quality requirement is made mandatory.

For example, in the USA, ASME SA106-grB is a "fully killed" piping material and is approved by the ASME B31.1 Power Piping Code.