A 106 GRADE B MAXIMUM TEMPERATURE. 2

[sunnyjohn]

What is the maximum allowable temperature for use of ASTM A 106 Grade B. Can ASTM A 106 grad B material be used for superheated steam service at 420 degre celsius. Is there any limitations as per the code B31.1 for use at this temperature. If so can it be used for vent and drain lines.

 

[stanweld]

A-106 B can be used at your operating temperature using the design allowable stresses in Code.

 

[NozzleTwister]

The maximum temperature for A106, Gr. B is 426.67 deg. C. (800 deg.F.) per B31.1.

For vents and drains, I recomend using a minimum of Sch. 160 nipples regardless of what wall thickness calculations show is acceptable. The robustness will help prevent the connections from breaking off if they become bumped during construction or operation. Your branch will be with a 6000# weld-o-let.

NozzleTwister
Houston, Texas

 

[stanweld]

sunnyjohn,
Most Engineering specs that I see specify A-106 C for your design condition or choose P11/P12 low alloy steel.

 

[sunnyjohn]

However in one of the earlier replies in the same forum I notice that the recommended continous use, maximum temperature to be as 412 Degree celsius. Can any one clarify.
Also the use of P11/P12 , what is the maximum allowable continous operating temperature.

 

[metengr]

ASME B&PV Code, Section II, Part D, permits the use of both alloy steels (P11/P12) to approximately 649 deg C (1200 deg F). Depending on the service application (pressure containing external piping versus gas ducts or sheet metal housing) , I would recommend limiting this material to 565.6 deg C (1050 deg F).

 

[metengr]

I see you were interested in Power Piping. For B31.1 Piping applications, the maximum design temperature for P11 and P12 alloys is 593 deg C (1100 deg F).

 

[JohnBreen]

Hello,

ASTM A-106, Grade B, carbon steel should not be used at temperature above 800 degrees F (427 degrees C). See the notes in ASME B31.1 and B31.3, Appendices "A".

"Conversion of carbides to graphite may occur after prolonged exposure to temperatures over 427 degrees C (800 degrees F)."

This is referred to as "carbon migration". When you move the carbides out of the metal grains to within the grain boundaries the material become brittle (ductility is lost).

Regards, John.

 

[davefitz]

Also note B31.1 par 102.2.4 only allows overheat and ovepressure when the part is operating at temperatures for which it provides allowable stresses. This means that a short term overheat above 800F is not permitted, even though it is unlikely that short term overheats would lead to graphitization.

This often becomes an issue for designing power plant cold reheat piping- turbine trips or startup transients can cause the HP exhaust to overheat to 900 F.