Selection of electrode

kareem.021181 · **Posted:** Fri Apr 16, 2010 4:57 pm

Material of Tube – SA 209 T1, Normalized & Tempered, Diameter 57 mm OD, Thick 5.1 mm, Impact tested, Design temperature - 260°C, MDMT is -5°C,Service –Flue gas

Material of Tube sheet -- SA 336 F1, Normalized & Tempered ,Thick 99 mm, Exempt from Impact test, Design temperature - 400°C, MDMT is -5°C, Service –Water

PWHT - 610°C±10°C, t=2h 30 min

Tube light expansion 3÷5% after tube to tube sheet welding

This vessel is in service for 1 year. There is erosion in the tube to tube sheet joint. Manufacturers WPS is not available.

My Question is –
1. What are the things I should consider in choosing an electrode? & what electrode should I choose – SMAW? GTAW?
2. What are the things I should consider in qualifying a WPS.

kareem.021181 · **Posted:** Sun Apr 18, 2010 10:04 pm

kareem.021181 wrote:

Material of Tube – SA 209 T1, Normalized & Tempered, Diameter 57 mm, Thick 5.1 mm, Impact tested, Design temperature is 260°C, MDMT is -5°C, Service – Flue gas

Material of Tube sheet -- SA 336 F1, Normalized & Tempered ,Thick 99 mm, Exempt from Impact test, Design temperature is 400°C, MDMT is -5°C, Service –Water

PWHT - 610°C±10°C, t=2h 30 min

Tube light expansion 3÷5% after tube to tube sheet welding

This vessel is in service for 1 year. There is erosion in the tube to tube sheet joint. Manufacturers WPS is not available.

My Question is –
1. What are the things I should consider in choosing an electrode? & what electrode should I choose – if SMAW? if GTAW?
2. What are the things I should consider in qualifying a WPS.

svghate · **Joined:** Thu Aug 21, 2008 9:08 am **Posts:** 34

Check P number from QW 422 Table. Later see UNS number and chemical composiion and as well as minimum UTS. Elecrode selected shall meet minimum UTS requirement and also to meet nearest chemical composition of parent material. If there is difference in UTS then you may opt minimum of two.

Prepare draft WPS and weld test coupon. Carry out PWHT (socking time atleast 80% what is needed for the job) and carry out UTS, bend and impact as per requirement. If you are not getting full thickness speciman for impact testing then refer Table UG 84.2 to decide test temperature.

Selection of electrode

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