Our company procedure says PWHT shall meet 730+-15 deg C )for P-5A (2.25Cr-1Mo
Base Metal (P-No.)
Temperature °F / °C
Minimum Hold Time1 (hr)
P-5A (2.25Cr-1Mo)
1350 ± 25°F / 730 ± 15°C
2
Our fabricator procured this material and in their PWHT procedure has Holding temperature...
Regarding Point 4: Tempering temperature is equivalent to lower critical temperature A1
For SA 335 P22 -lower critical temperature mentioned is 805 deg C .
But in the material certificate tempering is done at 740 deg C
So can PWHT temperature be above 740 deg C?
1. PWHT temp for P22 material -kept at 730+-15 deg C
- is this prevent prevent cracking of the weld
2.What is the optimum cooling rate after PWHT
3. Is post heat important for P22 welding
4."After welding, PWHT temperature is kept below the parent material tempering temperature by...
P22 Piping materials Tempering process carried out at typically 740degC. Whether PWHT holding temperature for P22 material can be above tempering temperature?
In the below thread there is a comment
The code committee, for various reasons, changed the factor against ultimate from 4 to 3.5 starting with the 1999 Addenda. Factors against yield, time dependent, and compressive did not change.
what are the current factors against yield,time dependent and...
For SA-106 Grade B pipe ,After 375 deg C the max allowable stress values are time dependant. Notes T1 & G10 ASME sec II Part D
NOTES — TIME-DEPENDENT PROPERTIES
T1 Allowable stresses for temperatures of 370°C and above are values obtained from time-dependent properties.
G10 Upon prolonged...
Hi
Derating of process piping
I want to know whether derating can be applied in the below scenario.
This is a modification of existing syngas line which is 15 years old. The current piping is designed to 550 deg C and pressure to 52 bar
But there is an alarm in the system at 285 deg C.
My...
In what circumstances design temperature of a piping system can be changed?
-In a operating plant ,the operating temperature of a particular pipe system (where alteration/Modification required) is max 300 deg C,above which there will be alarm/Trip.But the piping is designed to a higher...
I have a query regarding Isolation valves in syngas service.
Current Valve size is 16"(400NB)class 600
Temperature 293 deg C
Pressure 35 Bar
Current Valve is a GATE VALVE.
What are the pros and cons of using a BALL VAlVE in the place of above GATE VALVE.
DV
No current plan to install gas detectors on flanges .
No existing detectors present for valve stem leak. How important is individual gas detection for these valves?
Currently there are gas detectors placed at different location at site and also regular manual check for flanges etc.
Also...
