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SA355 P11 To SA335 P22 Welding

09/12/2015 1:49 PM

Please confirm if the filler metal ER90S-B3 and E9018-B3 is good choice for welding p22 to p11

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Anonymous Poster #1
#1

Re: SA355 P11 TO SA335 P22 WELDING

09/12/2015 1:59 PM

Sure. That is fine. I do it all the time.

You can never go wrong asking total, anonymous strangers on an anonymous forum questions like this.

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Re: SA355 P11 TO SA335 P22 WELDING

09/12/2015 2:10 PM

"For P11 (1 ¼% Cr - ½% Mo) chrome-moly pipe, use either an AWS E8018-B2 H4R or E8018-B2L H4R SMAW electrode, as both are formulated for applications subject to high heat and/or humidity. They also resist hydrogen pick up that can lead to cracking or starting porosity. The E8018-B2L H4R stick electrode contains a lower amount of carbon, which further protects against cracking. Both electrodes work especially well on boiler and similar piping repairs that require weld tensile strengths above 80,000 psi. On the average they offer tensile strengths in the range of 90,000 to 98,000 psi.

P21 (2 ¼% Cr - 1% Mo) or P22 (3% Cr - 1% Mo) pipe requires SMAW electrodes with higher chrome content and higher tensile strengths than those used for P11 pipe. Options include AWS E8018-B3L, E9018-B3 H4R or E9018-B3L H4R electrodes, which are good for boiler work and general piping applications. These SMAW electrodes yield tensile strengths in the range of 105,000 to 110,000 psi and generally feature a special moisture resistance coating that protects against hydrogen pick up in service conditions of high humidity or heat."

"To select low alloy filler metals, it is first important to understand chrome-moly pipe itself. Among the more common grades are P11, P21, P22, P91 and P92, some of which can withstand service temperatures over 1112 degrees Fahrenheit (600 degrees Celsius) and have wall thicknesses ranging from 1/8 inch to eight inches. The amount of chrome, molybdenum or other alloying elements determines the assigned grade of chrome-moly. These particular grades contain a range of 1¼ to 9 percent chrome and ½ to 1 percent molybdenum, with those containing more chrome providing the most corrosion and temperature resistance. Not surprisingly, the amount of chrome is also a determining factor in filler metal selection.

When welding chrome-moly pipe, regardless of the grade and/or the filler metal being used, it is important to maintain specific preheat and interpass temperatures. Consistent temperatures help conserve strength and crack resistance under extreme service conditions. Recommended preheat temperatures range from 250 to 400 F (121 to 204 C) according to the wall thickness (see Figure 1).Per AWS code D10.8-96, 'Recommended Practices for Welding of Chromium-Molybdenum Steel Piping and Tubing,' preheating practices should always be observed, even before tack welding. It is especially important to preheat prior to repairing P21 and above grade chrome-moly pipe that has been in service, as it may experience temper embrittlement or ductility loss. This can occur when the pipe has been exposed to temperatures above 850 F (450 C) for an extended period of time (ref. AWS D10.8-96, 5.1 and 7.2).

Maintaining interpass temperatures is also important. A range of 350 to 600 F (177 to 316 C) is typical, depending on the grade of chrome-moly and its thickness, but most importantly, upon the required welding procedure.

Post-weld heat treating (PWHT) or stress relieving is also recommended. PWHT requirements are generally 1150 to 1400 F (621 to 760 C) for one hour. PWHT helps rid the weld of hydrogen that may have been picked up either from the filler metal, the base metal, or the atmosphere, and can help minimize the chances of cracking. Most low alloy filler metals designed for chrome-moly applications will also provide recommended stress relieving temperatures and duration on the label or spec sheet."

http://www.hobartbrothers.com/index.php?mact=News,cntnt01,print,0&cntnt01articleid=37&cntnt01showtemplate=false&cntnt01returnid=523

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#3
In reply to #2

Re: SA355 P11 TO SA335 P22 WELDING

09/12/2015 2:35 PM

additionally...

"A: The A335 P22 is a 2 ¼ Cr - 1 Mo material and A335 P11 is 1 ¼ Cr - ½ Mo material being joined to the plate material that is also 1 ¼ Cr - ½ Mo material. With these alloys the rule of thumb is to match the lower alloy material as would be the case with the A335 P22 material to the A387 Gr 11 plate material. In both cases, you could use a "B2" filler metal. The next issue in filler metal selection is the use of post weld stress relief which is not mentioned. If the weld is going to be subjected to a post weld stress relief then use an ER80S-B2 and if there will be no post weld stress relief you should consider ER70S-B2L."

http://weldingdesign.com/archive/correct-electrode-selection-key-welding-out-position

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