Homebred Anchor Flanges Used in Pipeline Project
are critical components for the heavy caliber and high internal pressure remote gas transmission and injection pipeline systems. It is also suitable for many process stations and line valve boxes in West to East Pipeline Project.
In general, anchor flanges are welded on the main transmission pipeline. It is half buried in the ground while fastened by cement heading. Pipelines under the ground suffer from uneven pressures from earth and water, and those on the ground face the threats from wind, snow, earthquake, etc. at the same time. Therefore the anchor flanges on the pipelines are used to prevent from excessive displacement of the piping.
Nations around the world are doing researches on the manufacture and application of anchor flanges, yet get few results. China has started its independent innovative research on this product from 2002 and made series of new achievements. The production of domestication anchor flanges greatly satisfy the needs of national key projects and promote scientific development of remote gas and petroleum transmission pipeline project.
1. Structural design of anchor flanges.
Both anchor flanges and pipelines bear complex forces, thus intensity and rigidity test, evaluation on anti-fatigue, anti-seismic and brittle fracture resistant capability are all necessary. However, calculation of some stress is still beyond our current ability and no unified manufacturing standard is stipulated. In order to simplify production process, we usually sort the anchor flanges with different working conditions and merge them into several categories. And then, we must calculate and confirm the structure size with the most rigorous situation of imposed stress.
2. The selection of raw materials.
According to Design Specifications on Gas Pipeline Process, materials of piping attachments and pipelines should be the same or at least similar to each other once they are connected through welding.
Raw materials of anchor flanges originally were the same materials of pipeline steel. However, this proposal is rejected by the fact that the steel is difficult to do controlled rolling and cooling production. After considering all related technical factors, the improved Erack Frcc 62 steel is adopted.
3. Forming and manufacture technology.
Anchor flanges are important components that used to fasten pipelines. It requires great product quality. Plastic forming and heat treatment are two key processes in manufacture. The internal structure of anchor flanges can not be thick with even crystalline grains before adequate plastic forming and reasonable heat treatment. Besides, heat treatment also greatly influences cost and energy.
4. Test for quality and performance.
To ensure that all anchor flanges are of good quality, tests for mechanical property and metallographic structure are required. What’s more, there are also nondestructive test and color penetrating test. In order to make sure security and reliability of anchor flanges, we also prepare pressure bending test for the products.
5. Mechanical treatment, antiseptic treatment and packaging.
On the base of technical requirements, anchor flanges must undergo rough machining and unltrasonic flaw detection before heat treatment. Antiseptic treatment is needed ahead of delivery.