Do you know the allowable deviation of the outer diameter and wall thickness of the national standard industrial pipeline

In industrial production and construction,pipeline is an important facility for fluid transportation,and its quality and safety are directly related to the stable operation of the whole system.The outer diameter and wall thickness of a pipeline are one of the key parameters that affect its performance.Therefore,the state has formulated a series of standards to regulate the allowable deviation of the outer diameter and wall thickness of industrial pipelines to ensure the reliability and safety of pipelines under various working conditions.This paper will introduce in detail the permissible deviation of outer diameter and wall thickness of several common national standard industrial pipelines.

First,"Seamless steel pipe for fluid transportation"GB/T8163-2018

The GB/T8163-2018 standard is applicable to hot-rolled and cold-drawn(cold-rolled)ordinary carbon steel,high-quality carbon steel,low-alloy steel and ordinary alloy structure seamless steel pipes,which can be used as pipes for transporting various fluids.

1.Allowable deviation of outer diameter

For hot-rolled(expanded)steel pipes,the allowable deviation of the outer diameter is±1%D or±0.5mm,which is the larger value.Here D represents the nominal outside diameter of the steel pipe.

For cold-drawn(rolled)steel pipes,the allowable deviation of the outer diameter is±0.75%D or±0.3mm,the larger value is also taken.

2.Wall thickness tolerance

For hot-rolled(expanded)steel pipes,the wall thickness tolerance varies according to the relative ratio S/D of the nominal outer diameter D of the steel pipe and the wall thickness S,which is specified as follows:

When S/D≤0.10 and the nominal outer diameter of the steel pipe D≤102mm,the allowable deviation is±12.5%S or±0.4mm,whichever is greater.

When S/D≤0.10 and the nominal outer diameter of the steel pipe D>102mm,the allowable deviation is±15%S or±0.4mm,which is the greater.

When 0.10<S/D≤0.05,the allowable deviation is±12.5%S or±0.4mm,whichever is greater.

When S/D>0.10,the allowable deviation is±12.5%S to-10%S.

For heat-expanded steel pipes,the wall thickness tolerance is±17.5%S to-12.5%S.

For cold-drawn(rolled)steel pipes,the allowable wall thickness deviation varies according to the nominal wall thickness S of the steel pipe,and the specific provisions are as follows:

When S≤3mm,the allowable deviation is±15%S to-10%S,or±0.15mm,which is the larger value.

When 3mm<S≤10mm,the allowable deviation is±12.5%S to-10%S.

When S>10mm,the allowable deviation is±10%S.

Second,"Seamless steel pipe for petroleum cracking"GB/T9948-2013

"Seamless steel pipe for petroleum cracking"GB/T9948-2013 standard is applicable to furnace tubes,heat exchanger tubes and pipe tubes.These steel pipes are mainly used in the petroleum cracking process,so the precise control of their outer diameter and wall thickness is strictly required.However,the specific outer diameter and wall thickness tolerance are not listed in detail in this standard,and need to be determined according to the specific application scenario and manufacturer's specifications.

Third,"Seamless steel pipe for high-pressure fertilizer"GB/T6479-2013

The GB/T6479-2013 standard is suitable for pipelines with nominal pressure of 1032MPa,working temperature of-40400℃,and transportation medium of synthetic ammonia raw gas(hydrogen/nitrogen),ammonia,methanol,urea,etc.The size and quality of these steel pipes shall comply with the provisions of the GB/T17395-2008 standard.

The allowable deviation of the outer diameter and wall thickness of the seamless steel pipe for high-pressure fertilizer is also not listed in detail in the GB/T6479-2013 standard,but the relevant provisions of GB/T17395 should be followed.The specific value needs to be determined according to the material,specifications and conditions of use of the steel pipe.

Fourth,"Seamless steel pipe for low and medium pressure boilers"GB/T3087-2022

"Seamless steel pipe for low and medium pressure boilers"GB/T3087-2022 standard is suitable for superheated steam pipes and boiling water pipes for low and medium pressure boilers of various structures made of low carbon steel.

1.Allowable deviation of outer diameter

For hot-rolled(expanded)steel pipes,the allowable deviation of the outer diameter is±1%D or±0.5mm,which is the larger value.

For cold-drawn(rolled)steel pipes,the allowable deviation of the outer diameter is±0.75%D or±0.3mm,the larger value is also taken.

2.Wall thickness tolerance

The wall thickness tolerance of seamless steel pipes for low and medium pressure boilers is not listed in detail in this standard,but it should generally follow a similar specification to seamless steel pipes for fluid transportation,and the specific value needs to be determined according to the material,specifications and conditions of use of the steel pipes.

Fifth,"Seamless steel pipe for high pressure boiler"GB/T5310-2023

"Seamless steel pipe for high-pressure boilers"GB/T5310-2023 standard is applicable to the manufacture of high quality carbon structural steel,alloy structural steel and stainless heat-resistant steel seamless steel pipe for pipelines with high pressure and above pressure.

For the outer diameter and wall thickness allowable deviations of seamless steel pipes for high-pressure boilers,the standard does not list the specific values in detail.However,the size and quality of these steel pipes should usually meet the provisions of the relevant national standards to ensure their safety and reliability in practical applications.

6."Seamless Stainless Steel pipe for Fluid Transportation"GB/T14976-2012

"Seamless stainless steel pipe for fluid transportation"GB/T14976-2012 standard is applicable to stainless steel hot-rolled,hot-extruded and cold-drawn(cold-rolled)seamless steel pipes,which are mainly used in the chemical and petroleum industries with highly corrosive media pipelines.

For the outer diameter and wall thickness allowable deviations of stainless steel seamless pipes for fluid transportation,the standard also does not list the specific values in detail.However,the outer diameter and wall thickness of these steel pipes should comply with the provisions of relevant national standards to ensure their corrosion resistance and mechanical strength in practical applications.

7.General requirements for pipe wall thickness deviation in national norms

In addition to the above specific standards,the state has also made general provisions on pipe wall thickness deviations.According to the"Petrochemical Design Code"and other documents,the wall thickness of the pipeline should meet the design requirements,and should not exceed plus or minus 10%of the wall thickness of the pipeline.This regulation aims to ensure the mechanical strength and safety of the pipeline and prevent accidents such as oil spills during long-term operation.

For special industries,such as oil pipelines,the state stipulates that the wall thickness deviation should not exceed plus or minus 5%of the wall thickness.These stricter regulations are in order to ensure the safe operation of pipelines under harsh conditions such as high pressure and high temperature.

Eight,the importance of pipe wall thickness deviation

The control of pipe wall thickness deviation is very important to ensure the safety and reliability of pipe.If the wall thickness deviation of the pipeline is too large,it will cause distortion,deformation,plastic deformation and other phenomena of the pipeline during operation load,and then cause serious accidents such as pipeline failure,oil leakage or explosion.

Therefore,in the actual pipeline construction and production process,the pipe wall thickness deviation standard stipulated by the state must be strictly observed,and the quality must be strictly inspected and controlled.Through scientific design,fine management and strict inspection,it can ensure the safety,reliability and durability of the pipeline in use.

7.Summary

The allowable deviation of the outer diameter and wall thickness of the national standard industrial pipeline is an important parameter to ensure the quality and safety of the pipeline.Different standards of steel pipes have different outer diameter and wall thickness allowable deviation regulations,which are usually determined according to the material,specifications and conditions of use of the steel pipe.

In practical applications,it is necessary to strictly abide by relevant national standards and specifications,and precisely control the outer diameter and wall thickness of pipelines.Through scientific design,fine management and strict inspection,it can ensure the safety and reliability of the pipeline under various working conditions,and provide a strong guarantee for China's industrial production and construction.

It is hoped that the introduction of this paper can help readers better understand the relevant provisions of the allowable deviation of the outer diameter and wall thickness of the national standard industrial pipeline,and provide references for the design,construction and maintenance of pipeline engineering.Let us work together to improve the safety management level of industrial pipelines and create a better future.