Dear,
When welding according to an approved Welding Procedure Specification (WPS) for a shell course with a 60-degree bevel fit-up, and then needing to fabricate a thicker shell course, it is crucial to ensure the bevel angle is appropriate for the increased thickness. The following considerations will help determine the appropriate bevel angle for a 130mm thick shell course, assuming materials are ASTM A36 and the design code is API 650:
Standard Bevel Angles: For thicker materials, bevel angles are adjusted to ensure proper penetration and weld quality. While a 60-degree included angle is commonly used for thinner sections like 8mm, thicker sections often require adjustments to the bevel angle to accommodate the increased volume of the weld metal and ensure adequate fusion.
API 650 Recommendations: API 650 does not prescribe specific bevel angles but emphasizes the importance of joint design to ensure quality and structural integrity. Generally, the bevel angle must provide sufficient access for welding and ensure proper fusion.
Typical Bevel Angles for Thick Plates:
- For plates up to 25mm (1 inch), a typical included angle is 60 degrees.
- For plates from 25mm to 50mm (1 to 2 inches), the included angle may reduce to around 45-50 degrees.
- For plates thicker than 50mm, included angles often range between 30 to 45 degrees, with considerations for double-sided welding and multi-pass welding techniques.
Fabrication Practices: For a 130mm thick shell course, it is common to use a compound bevel or a J-groove to reduce the amount of weld metal required and to facilitate better welding conditions.
Given these considerations, an appropriate approach for a 130mm thick shell course with ASTM A36 material under API 650 might include:
- Single-V Bevel: If using a single V-bevel, an included angle of around 30-45 degrees might be appropriate. This angle allows for deep penetration while managing the volume of weld metal needed.
- Double-V Bevel: For very thick plates, a double-V bevel could be used to balance the welding from both sides, typically with each side having an included angle of around 30 degrees.
Recommendation: For a 130mm thick shell course, a 30 to 45-degree bevel angle should be appropriate. A double-V bevel (each side 30 degrees) might also be considered for such thickness to ensure welding quality and manage distortion.
Always ensure that any change in bevel angle or welding parameters is reflected in an updated WPS, approved by the relevant authority or quality assurance team, to maintain compliance with API 650 and ensure structural integrity.
AB
Concern is to confirm that i am welding as per approved WPS 8 mm Shell course with 60 degree bevel fit-up both sides, and if i fabricate 130mm thick shell course weld what should be the appropriate bevel degree (As i don't have WPS now in my hand).--Materials are M.S. A36 for both tanks.Designing Code is API 650Regards,Mashood Ahmed KhanEPIC Pvt. Ltd.P:03462794988, 0309-8885421"The man who best understands time is he who is not taken aback by its proceedings."(Ali Ibn Abi Talib)
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