# Calculation and determination of thickness and width of stainless steel welded pipe materials

by yane Yang Sales Manager
The steel strip or steel plate selected for the stainless steel welded pipe is first considered for its thickness. Use reasonable and correct thickness to ensure and meet the basic requirements of the product. The thickness of the selected steel strip or sheet is determined by the minimum allowable wall thickness of the stainless steel welded pipe, but it must also consider the factors affecting the wall thickness of the stainless steel welded pipe during the production process, such as forming, welding, weld grinding, etc. It is possible to make the thickness of the stainless steel welded pipe thinner. Therefore, the determination of the thickness of the material used for stainless steel welded pipe should consider the following various factors:
• Standard for the production of stainless steel welded pipes
• Nominal (standard) size (diameter × wall thickness) of stainless steel welded pipe;
• Stainless steel welded pipe wall thickness tolerance;
• The thickness tolerance level of the steel strip;
• Stainless steel welded pipe weld grinding margin;
• Safety factors.
The strip thickness obtained from the above factors is:
• T=t-k%t+∮+0.04+0.05
• Where t: standard wall thickness of stainless steel welded pipe
• K%: wall thickness tolerance (maximum k value is 10%)
• ∮: for steel strip thickness tolerance
• Grinding allowance: 0.04mm
• Safety factor margin: 0.05mm
Example:
• Stainless steel welded pipe standard size: 51 × 2.0mm
• Standard for the production of stainless steel welded pipes: GB/T12770
• Stainless steel welded pipe wall thickness tolerance: 10% t 2.00×10%=0.2mm
• Steel strip thickness tolerance level: +0.14mm
• Safety factor margin: +0.05mm
• Welded pipe weld grinding allowance: +0.04mm
• Minimum thickness of steel strip: 2.03mm (2.0 positive tolerance)
The calculation of the width of the stainless steel welded pipe is a very complicated problem, because in the production process of the stainless steel welded pipe, the factors affecting its outer shape are many, the change is large, and the law is difficult to grasp, and these are related to the width of the material used.
The dimensions of the stainless steel welded pipe are closely related to the material of the selected stainless steel, mechanical properties, material thickness, elongation of the material, forming method of the welded pipe production process and welding method. In this way, in calculating the width of the stainless steel welded pipe, the above factors must be considered.
The width of the stainless steel welded pipe shall be calculated from the required diameter and the pre-calculated wall thickness of the welded pipe, together with the influencing factors mentioned above. The most basic size is to give the theoretical width of the material. The theoretical width is the average diameter remaining in π, that is: π × (OD-t); where OD is the standard outer diameter of the stainless steel welded pipe, and t is the wall thickness of the stainless steel welded pipe, as shown in the following figure:

The following is a calculation formula for the width of the stainless steel welded pipe obtained after considering the theoretical width, welding and other influencing factors and the sizing allowance:
• L=π(OD-t)+14%t+0.5√ ̄OD
• Where the theoretical width: π (OD-t)
• Welding allowance: 14%t
• Sizing allowance: 0.5√ ̄OD
• L: width of stainless steel welded pipe
• t: steel strip thickness (mm)
• OD: Standard outer diameter (mm) of stainless steel welded pipe
Source: China Welded Pipes Manufacturer - Yaang Pipe Industry Co., Limited (www.yaang.com)