Q. Dear Sir, we have a combination of ASTM A387 Gr.11 with X2CrNi12. Would suggest an electrode for this one, please
Ans.
1.25Cr-0.5Mo steel is covered under ASTM / ASME A387 Grade 11, class 2 Chromium-Molybdenum alloy, used in a variety of industries and is highly effective, particularly in the oil, gas, and chemical industry, where liquids and gases are often stored at high-temperature pressure vessels. The higher levels of chromium also provide excellent corrosion and oxidation resistance.
X2CrNi12(1.4003) EN 10088 – 2 is a second-generation , Low C, Cr Ferritic Stainless-steel ( SS409) covered under ASTM S40977. Its composition is designed to produce fully ferritic with some alloy carbides in the microstructure. X2CrNi12 (SS 409) Ferritic stainless steels have excellent resistance to exhaust gas and atmospheric corrosion.
In this case, your 1.25 Cr- 0.5 Mo is P No. 4 & X2CRNI12 ferritic SS ( UNS S40977) is P. No. 7.
With reference to API RECOMMENDED PRACTICE 582, THIRD EDITION, MAY 2016, Welding Guidelines for the Chemical, Oil, and Gas Industries.
As per 6.2 Dissimilar Welding, under point No 6.2.2 States that ” When joining ferritic steels (P-No. 1 through P-No. 5 and P-No. 15E) To : b) ferritic stainless steels (P-No. 7) ”
First you have to select filler metal depending on your service temperature application, accordingly,
–Type 309 and Type 309L may be used for design temperatures not exceeding 600 °F (315 °C);
–For temperatures above 600 °F (315 °C), Nickel-base filler metals are suggested to adjust high differential thermal expansion
API 582-16, also suggest the nickel-base alloy filler materials using design conditions and service environment.
–API 582-16, Table 2 has been reproduced from the reference to explain the use of Nickel based filler metal suitable for design service temperature and Sulphidation or Non -Sulphidation environment.
| ASME/AWS Filler 1 Material Classification | Maximum Design 2 Temperature (Non-sulfidation Environment) | Maximum Design Temperature (Sulphidation Environment) |
| ENiCrFe-3 | 1000 °F (540 °C) | 700 °F (370 °C) |
| ERNiCr-3, ENiCrFe-2 | 1400 °F (760 °C) | 750 °F (400 °C) |
| ERNiCrMo-3, ENiCrMo-3 | 1100 °F (590 °C) | 900 °F (480 °C) |
NOTE 1 Comparable FCAW consumables may be applied for dissimilar welding applications, provided they are approved by the purchaser.
NOTE 2 Refer to API 939-C for the definition of sulfidation.
According to NOTE 2 given below under Table 2 (API 582-16), If your service condition is exceeding the temperature stated in the Table 2. You are advised to confirm filler metal selection with the filler metal supplier or client.
Apart from this, be advised to consider Pre-heat, PWHT guidelines as per the applicable code. However, these are the recommendations, Procedure qualification run is highly recommended.
Acknowledging special thanks to Mr. Prem Jobanputra , Welding Engineer, L&T, Ranoli Works, Baroda. Gujarat, L&T Sponsored, M.E. Welding Tech Program. The M.S.University of Baroda, Gujarat, India.for providing the proper reference material to handle this query.
Reference:- API RECOMMENDED PRACTICE 582, THIRD EDITION, MAY 2016,Welding Guidelines for the Chemical, Oil, and Gas Industries.
We hope this information is useful to you!
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