How to identify the level of corrosion in a gas pipeline

There are three types of corrosion in pipelines: mild, moderate and severe.

Among them, mild refers to floating rust and patent peel falling on the surface of the pipe, moderate is a large area of rust, and the depth of the pit of the pipeline rust does not exceed two millimeters, and severe refers to the depth of the corroded pit exceeds two millimeters. Inspectors will carry out maintenance immediately after discovering heavily corroded pipelines, and mild and moderate pipes will generally be maintained at the end of the maintenance period because there are no safety problems, so the public does not need to worry.

In addition to the coating condition of the pipeline itself, the factors affecting the corrosion of buried metal pipelines are also affected by the environmental factors of pipeline burial. When the corrosion protection system of the pipeline is tested, the corrosive environment is generally also tested, and the corrosive nature of the pipeline environment is analyzed, so as to determine the trend of corrosion of the pipeline. Environmental factors can be broadly divided into two categories: soil factors and non-soil factors.

The former is directly related to soil properties, while the latter is caused by electrical factors. The main soil factors affecting the corrosion of buried pipelines are soil resistivity, soil moisture content, and soil permeability (redox).

condition), soil acidity, and soil salinity and composition.

The non-soil factors that cause the corrosion of buried pipelines are mainly stray DC currents and alternating current induced by high-voltage transmission lines in the soil, which can lead to electrical corrosion of pipelines.

Gas Pipeline Corrosion Grading Judgment Pipeline Corrosion Grade 1 Condition Normal Pipeline Corrosion Grading Judgment Diagram Handling No follow-up Slight rust Grade 2 Gas pipe rust to yellow rust Galvanized pipe The surface layer falls off slightly.

The nominal pressure of low-pressure pipelines does not exceed the nominal pressure of medium-pressure pipelines, and the nominal pressure of high-pressure pipelines is 10-100MPa, and the nominal pressure of ultra-high-pressure pipelines exceeds 100MPa

Long-distance pipelines that meet one of the following conditions are GA1 class: a) pipelines that transport toxic, flammable and explosive gas media with a design pressure of >;b) Pipelines with a conveying distance of 200km (Note 1) and a nominal diameter of DN 300mm for transporting toxic, flammable and explosive liquid media;c) Conveying slurry medium, conveying a pipeline with a distance of 50km and a nominal diameter of DN 150mm.

A long-distance pipeline that meets one of the following conditions is GA2 class: a) a pipeline that transports toxic, flammable and explosive gas media with a design pressure of P;b)long-distance pipelines outside the GA1B);c) long-distance pipelines outside the GA1C) range.

The public pipelines are GB, and the levels are divided into: GB1 and gas pipelines; GB2, thermal pipes.

Industrial pipelines that meet one of the following conditions are classified as GC1: a) pipelines that transport extremely hazardous media in GB5044 "Classification of Occupational Exposure to Toxic Hazards"; b) Pipelines transporting GB50160 "Code for Fire Protection Design of Petrochemical Enterprises" and GBJ16 "Code for Fire Protection Design of Buildings" with fire hazard of Class A and B combustible gas or Class A flammable liquid medium and design pressure P; c) Conveying flammable fluid medium and toxic fluid medium, with design pressure p and design temperature greater than or equal to 400 pipes; d) Pipes that transport fluid media and are designed with pressure p.

Industrial pipes that meet one of the following conditions are GC2 grade:

a) Pipelines that transport GB50160 "Code for Fire Protection Design of Petrochemical Enterprises" and GBJ16 "Code for Fire Protection Design of Buildings" with fire hazard of Class A and B combustible gas or Class A flammable liquid medium and design pressure P"; b) Pipes that transport flammable fluid media and toxic fluid media with a design pressure of P and a design temperature of 400; c) Pipes that transport non-flammable fluid media and non-toxic fluid media with a design pressure of p and a design temperature of 400; d) Pipes that convey fluid medium with a design pressure of p and a design temperature of < 400; Note 1: The conveying distance refers to the direct distance between the place of origin, the storage warehouse, and the user for transporting the commodity medium.

Broadly understood, pressure pipes refer to all pipes that are subjected to internal or external pressure, regardless of the medium inside the pipe. The pressure pipeline is a part of the pipeline, which is used to transport, distribute, mix, separate, discharge, measure, control and stop the flow of fluids, and is composed of pipes, pipe fittings, flanges, bolts, gaskets, and valves.

The assembly assembly composed of other components or pressure parts and supporting parts is sorted out according to TSGR1001-2008 "Pressure Pipeline Installation Permit Rules" and "Industrial Pressure Pipeline Safety Technical Supervision Regulations", and the pressure pipeline is divided into: GA (long-distance pipeline), GB (public pipeline), GC (industrial pipeline), GD (power pipeline).

Class 2GA (long-distance pipelines) is further divided into: Class GA1 and Class GA2; GB (public pipes) are further divided into: GB1 and GB2; GC (industrial pipes) are further divided into:

GC1, GC2, GC3; GD class (power pipeline) is further divided into: GD1 and GD2.

The design will be explained for different media situations. Generally thought to be the boundary.

A reasonable pipe wall thickness can be expressed by the pipe table number (SCH) to indicate the wall thickness series. This is specified in the 1938 American National Standards Institute Standard for Welded and Seamless Steel Pipes.

The pipe table number (SCH) is the ratio of the design pressure to the allowable stress of the material at the design temperature multiplied by 1000 and rounded. Namely: sch

p/[ó]t×1000。where p—design pressure, mpa; [t—allowable stress of the material at design temperature, mpa.]

The grading criteria are as follows:

1. Vacuum pipeline p<0MPa.

2. 0 p for low-pressure pipelines.

3. Medium-pressure pipelines, high-pressure pipelines 105, ultra-high-pressure pipelines P>100MPa.

The special equipment catalogue attached to the announcement of the General Administration of Quality Supervision, Inspection and Quarantine on revising the "Special Equipment Catalogue" (No. 114 of 2014) issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on October 30, 2014 clearly stipulates that: Pressure pipeline refers to the tubular equipment used to transport gas or liquid with a certain pressure.

The range is specified as the maximum working pressure is greater than or equal to the gauge pressure), the medium is gas, liquefied gas, steam or flammable, explosive, toxic, corrosive, the maximum working temperature is higher than or equal to the standard boiling point of the liquid, and the nominal diameter is greater than or equal to 50mm of the pipeline.

Classification criteria: du

1. P<0MPa vacuum pipe.

zhidao

2,0 p low-pressure pipeline version.

3,,105,P>100MPa ultra-high pressure pipeline.

Pressure pipe bai channel design.

The classification of categories and levels is extracted from the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China (DAOTSG Technical Specifications for Special Equipment) TSGR1001-2008 "Rules for the Design and Licensing of Pressure Pipelines and Return Pressure Pipelines", issued: January 8, 2008, implemented: April 30, 2008 (referred to as the new rules); 1.

Appendix B Pressure Pipeline Category, Class B1GA (Long-distance Pipeline).

Outdoor risers and overhead pipes are painted yellow, and indoor galvanized pipes are painted with silver.

The table you came with is correct, 3MPa is high pressure, it is said to be ultra high pressure, that was before, and now you are going to be stupid according to the pressure you attached.

Gas pipes are generally galvanized pipes, which should not be rusty, which may be caused by poor pipe quality. Slight surface rust is not a big problem, and it can be sanded with an abrasive cloth and coated with anti-rust paint or silver powder paint, which will not affect the service life and will not cause air leakage.

It doesn't matter if it's local, but it's not okay if it's a large area, after all, it's a new house.

What you are talking about is the rust on the outside of the pipe, if it is a new house, you can find the developer to solve it, if the rust is serious, you must replace the pipe, but if the surface is shallow rusty, use sandpaper and steel brush to polish and then brush the anti-rust paint.

Hello answer, glad to answer your questions. I noticed that this problem means that I want to know the treatment of rust in natural gas pipelines at home, generally speaking, natural gas pipelines have a service life, and the average quality pipes need to be replaced in about a year. There will be staff from the natural gas pipeline company who will come to the door for maintenance, it is recommended to contact the natural gas company to come to the door for you to overhaul and measure whether there is any leakage in the air.

Here are three suggestions for your reference based on my opinions: 1. Contact the natural gas company, ask for on-site maintenance, detect the residual gas content in the air, and then choose the appropriate pipeline according to the suggestions. 2. Go to the hardware store by yourself, buy pipes of suitable length and excellent quality, and replace them by yourself. 3. Contact the property in the community, match the excellent quality pipeline, and go to purchase and replace.

Hello, if your problem has been solved, you can click on the upper right corner of "End Service" and give a 5-star like, your like will support me to continue to consult and help. Click on the avatar to follow me, if you have any other questions, you can ask me again, I hope my answer can help you

Dear, if you can, please give me a thumbs up, special thanks I am a senior in the workplace, a career counselor who continues to move forward on the road of helping others.

The yellow alert officer is obvious, easy to spot, and avoided.

The anti-corrosion of gas pipelines is very important, so the laid gas pipelines should be coated with yellow anti-corrosion identification paint or silver powder paint and coated with yellow identification rings;

My personal understanding is that "yellow" is more eye-catching, and yellow is generally used to indicate danger!