Engineering applications of stainless steel pipe fittings Stainless steel pipe fittings application standards

A, the actual selection and use of the corresponding regulations and the provisions of the pipe fittings

The actual selection or use of fittings, the first must follow the corresponding regulations and specifications within the provisions, especially the transport of extremely or highly hazardous fluid media, flammable media and high-pressure gas and other pipeline occasions. Under this premise, the type of fittings is determined mainly based on the application and use conditions (pressure, temperature, fluid medium). The following mainly lists the relevant regulations / norms, for reference only.

1、Special equipment safety supervision law;

2, special equipment safety inspection regulations listed;

3, pressure piping safety management and supervision provisions;

4, special equipment quality supervision and safety supervision regulations;

5, special equipment design / manufacturing / installation supervision and management regulations (proposed);

6, pressure pipeline safety and technical supervision procedures (prepared);

7, industrial metal pipeline safety technical specifications (prepared);

Second, the strength level of pipe fittings to determine

1, the nominal pressure to indicate its level or specify the pressure a temperature rating of the pipe fittings, the pressure a temperature rating should be specified in accordance with the standard as the basis for its use, such as GB / T 17185;;

2, the standard only provides the nominal thickness of the straight pipe connected to its fittings, according to the standard provisions of the benchmark pipe level to determine its applicable pressure a temperature rating, such as GB14383 ~ GB14626.

3, the standard only provides the shape of the size of the pipe fittings, such as GB12459, GB 13401, should be verified by the test to determine its compressive strength.

4, the other, should be designed according to the relevant provisions of the pressure or analytical analysis and other methods to determine its use benchmark. In addition, the determination of the strength level of the fittings, but also should not be less than the entire piping system in the operation of the most severe operating conditions that may be encountered under pressure.

Third, safety and economy

The actual piping project in the use of pipe fittings structure type, in addition to the above-mentioned, there are a variety of other structural forms of pipe fittings to meet a variety of different working conditions, especially the requirements of special working conditions. In the engineering design or selection, the higher the strength level of the fittings, the higher the security, but the cost of the project is also greater, will cause unnecessary waste.

Considered from the economic benefits of meeting the requirements of the project design while reducing costs as much as possible, but often easy to form the overall selection of pipe fittings appear a small number of multi-variety results, which is not conducive to on-site construction materials management, control and design changes required for material substitution. Therefore, the choice of pipe fittings, should be integrated security and economy, as far as possible to reduce the variety of pipe fittings appropriate. In addition, the site construction conditions, the level of construction, the procurement cycle of fittings and other factors, should also be in the selection of fittings to give the necessary attention. In specific cases, should also consider the possibility of using reinforced pipe joints, diagonal bends and small diameter pipe bending processing on site.

At the same time, the production capacity and products for the pipe fittings production plant, the market supply situation is also necessary to understand.

Fourth, the standard selection of pipe fittings in the problem

1, the domestic pipe fitting standards are not sound, mismatched pipe fitting standards should include the type of pipe fitting parameters standards and pipe material standards. But the material standards are either incomplete, or the lack of requirements such as Ting goods, inspection and group batch rules, quality certification and other aspects of the quality of technical requirements. Fitting material standards are poorly matched, often from their respective positions, perspective, rather than from the entire system of pressure piping standards to develop. The choice of engineering, pipe standards have, but no corresponding forgings or castings standards. The reality is that the forging standards for pipe fittings borrowed from the forging standards for pressure vessels, without taking into account the differences between the two, such as welding, filming inspection and other provisions.

2, the level of pipe fittings standards vary widely, the lack of consistency and systematic content, so that the interface appears contradictory, resulting in the use of inconvenience.

3, no type test standards for pipe fittings, only GB12459, GB13401 standard provides a seamless steel butt weld fittings and steel sheet butt weld fittings burst test pressure calculation, other to ensure the quality of pipe fittings manufacturing type test standards or implementation standards are not.

Steel metal fittings in order to meet the different uses, conditions, a variety of structural forms. One of the most used is the elbow, tee and reducer. The connection of pipe fittings are commonly used butt welding connection, socket welding connection and pipe thread connection. Usually, DN50 and above the pipeline using butt weld connection fittings, DN50 below the pipeline using socket weld fittings or threaded connection fittings plus sealing weld fittings type of selection, the first should be based on the design pressure of the pipeline system, design temperature and the nature of the medium in the pipe, followed by consideration of economy, life and other comprehensive factors, and according to the design pressure of the pipe system where it is located, design temperature to determine the use of fittings pressure a Temperature level. Branch pipe connection fittings from the main pipe branch pipe, if the same diameter, should try to use a tee connection; when the branch diameter is less than or equal to DN50, in the tee reducer range or applicable range outside, ding choose branch pipe table, half pipe joints or strengthen the pipe joints and other branch pipe connection fittings; In addition, according to the specific circumstances of the project can also be used on the main directly welded branch pipe structure, but must check the branch pipe Whether the connection needs to be reinforced.