As a matter of fact, modern manufacturing of black steel pipe has resulted in excellent grain structure and control of the mechanical properties of the pipes. These properties mainly include minimum yield strength, minimum tensile strength, ductility, impact strength, and harness. Some major piping manufacturers are capable of making black steel pipe that has the maximum yield strength up to 80 ksi. The flexibility offers a variety of customers the ability to optimize pressure and structural capabilities. As required, the composite wall thickness of black steel pipe can be increased and the stiffness of pipe system can be increased as well in order to resist the external loads. The most common and cost effective method used to increase the pipe system stiffness is to improve the quality of the backfill material and the level of backfill compaction.
Black steel pipes are traditionally transported to areas not so far from the pipe plants. However, for cross-region destinations, the traditional way no longer works well. Luckily, mobile manufacturing plants for black steel pipes are available in many parts of the world. With the mobile manufacturing plants, different kinds of black steel pipes can be produced. Quenching and tempering have great impact on the hardness of the black steel pipes and yield certain physical qualities. Therefore, different grades of black steel pipes would undergo different types of quenching and tempering in order to change their micro-structure to improve strength or properties.
Generally speaking, black steel pipes may have the following properties: adaptability to different applications such as water and wastewater transmission, pump station and treatment plant piping, circulating water lines for the power industry, penstocks, intakes and outfalls, aerial crossings, aqueducts, and trenchless. When designing a black steel pipe, the main consideration is the pipe’s ability to withstand internal pressure. After the wall thickness has been determined on the basis of the internal pressure, operating pressures, and transient pressures. What is more, the wall thickness must be checked to determine the adequacy for resisting external loads and the minimum thickness required for handling. External loads include those due to backfill material and potential vehicles, construction equipment, or railroad cars, and buckling the forces resulting from external pressure.
Normal temperature blackening mechanism is no consensus currently, because the black membrane is thin, usually no more than 3μm, use X-ray diffract meter and scanning electron microscope to analysis, normal temperature blackening film composition is not as alkaline black membrane Fe3O4, but its film layer components are more complex, it is difficult to make accurate judgments. The main technical indicators are: blackening agent is blue liquid, it’s no mechanical impurities, odorless, non-flammable, non-explosive, and non-corrosive, transport safety, its PH value is 2-2.5, the density is 1.04, and water insoluble matter is less than 1%. Its performance indicators are as follows: reference standards promulgated by the Ministry of Ordnance WJ535-82 <steel parts alkaline chemical oxidation technology>. After the black, the test results: 1. Experiment with 3% copper sulfate drip, discolored time is less than 32 seconds under 15-20℃. 2. Immersed it in the 3% sodium hydroxide aqueous solution for 2 hours will meet the standards.
The use methods: Framing→Degreasing(5-10mins)→Water rinsing(1min)→Rinsing(0.5min)→Derusting(1-5mins)→Water rinsing(1min)→Rinsing(0.5min)→GT-FH802 normal temperature blackening(2-6mins)→Water rinsing(1min)→Stabilizing(0.5-1min)→Immersing GT-FX238 rust oil dehydration(3-5mins) or GT-FB806 waterborne sealers(1min)→Drying or drying under 80-90℃(10-20mins). Pretreatment process including degreasing and rust-activated two processes, this is the key to black successfully in normal temperature, the general requirement is that the process black steel pipe should be degreased and rust thoroughly, only then can we get good black membrane. The circuit is: Medium temperature oil removing→Water rinsing→Rinsing→Derusting activation in normal temperature, light rust machined parts can use hydrochloric acid(the rate of industrial hydrochloric acid and water is 1:1), acid pickling 1-5mins, oxide scale thicker parts, can be derusted in 180-250g/l heated sulfuric acid→Water rinsing→Rinsing→GT-FH802 normal temperature blackening(this process is suitable for little oil, no thick Oxide scale parts, the processing time of each process in place, stable quality and low cost.). After learning the steps to operate the black steel pipe, you can use it correctly!
As we have introduced in our previous articles, there are various kinds of steel pipes both in domestic and international markets for your selection. The welded steel pipe is very popular among consumers both at home and abroad for many of its advantages actually. There are also countless kinds of welded steel pipes for your selection. Different kinds of pipes are created to satisfy different kinds of requirements both in our daily life and in commerical or industrial areas.
You can find the welded steel pipe very easily both in domestic and international markets. In order to ensure the normal function and to accomplish your work perfectly, you are advised to choose the best welded steel pipe with high quality which are made of the superior steel actually.
As you may know, there are also some foxy traders both at home and abroad who will provide the inferior pipe to consumers and with the same high price as the welded steel pipe price. It is a fact that most of us or consumers are the laymen to the steel pipe and they can't distinguish the superior pipe from the inferior ones actually. This will leave a potential risk to you since the inferior quality may cause damage or spoil.
One of the best way to find the best welded steel pipe is to select a reliable supplier. There are countless suppliers in the market. And you are advised to choose those have great reputaion among consumers for high quality and competitive price or the considerate services. Or you should try the brand welded steel pipe. Generally speaking, the brand product will provide a better quality and credibility assurance actually.
Nowadays, with the development of science and technology, online shopping has become more and more popular and convenient among consumers both at home and abroad since it is time-saving and effective. There are also countless suppliers of welded steel pipe online. Frankly speaking, Shanghai Xin Lin is one of the leading suppliers of steel pipe. We have great reputation among consumers both at home and abroad for our high quality and competitive price.
Fri Feb 21, 2014 3:21 pm
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