Comparison of ASTM A234 WPB Pipe Fittings and Domestic Carbon Steel Pipe Fittings Materials – Providing Piping Solutions

Comparing the Chemical Composition and Mechanical Properties of Domestic Carbon Steel Pipe Joints with ASTM A234 WPB Pipe Fitting In the standard specification and actual delivery value, the composition and purchasing performance index are selectively controlled. Domestic materials can fully meet the requirements of ASTM A234 GR.WPB to solve the problem of using GB standard materials to produce products in accordance with ASTM specifications.

In recent years, investment in foreign-funded domestic projects has increased year by year, and domestic capital investment in foreign projects has also increased. In these tenders, especially in the petrochemical, paper, energy, pharmaceutical and other fields, metal materials are becoming more international and the use of medium carbon steel materials is more common. On the other hand, due to the limitations of our national conditions, there is still some progress to be made in the internationalization of national materials, especially carbon steel materials. The market still needs to meet the requirements for its internationalization. Specific work in:

• (1) In some foreign investment projects or projects planned by foreign states, ASTM A234 GR.WPB (hereinafter referred to as WPB) material is selected for common carbon steel pipe fittings. ASTM A106 seamless steel pipe or ASTM A516 GR.60, ASTM A285 GR.C carbon steel plates are generally used for pipe joints that meet this requirement. According to the current situation of domestic resources, domestic steel mills can order batches in the case of a batch order, but in many cases, e.g. B. If the investment scale of the project is not large, demand cannot meet the batch, or design changes are required at the later stage of the project to provide a small number of products, the corresponding raw materials cannot be purchased from the Marketplace.
• (2) After some projects using WPB materials come into operation, daily maintenance, repair, remodeling and other works still require related WPB materials, often in urgent need. At this time, it is particularly important to solve the raw material problem in a timely manner.

At the same time, the carbon steel material resources of domestic materials such as 20# seamless steel tubes and Q235 steel plates are extremely rich; The resources on the market are sufficient and you can purchase them at any time. This article aims to make a preliminary comparison between the world's most commonly used WPB carbon steel material for pipe joint production and the domestic carbon steel material for pipe joints. Its objective is to try to discover the conditions under which the two materials can be substituted for each other, to solve the problem of using GB standard materials for the manufacture of products according to ASTM specifications, to explore the possibility of locating joints of pipes carbon steel and solve the domestic demand for WPB pipe fittings.

1. Carbon Steel Material for Household Pipe Fittings

At present, there are many national manufacturing standards for carbon steel welded pipe joints. These mainly include national standards GB 12459 and GB/T 13401, as well as industrial standards such as SH 3408, SH 3409, HG/T 21635 and HG/T 21631 and industrial standards such as electricity and petroleum. However, depending on the type of material used, there are up to two categories. One is seamless steel pipes for making seamless pipe joints and the other is steel plates for making welded pipe joints. The most commonly used standards for these two types of materials are listed in Table 1. Typical materials used for carbon steel welded pipe joints are GB 8163-20#, GB 5310-20G and GB 3274-Q235A, Q235B. The main chemical compositions and mechanical properties of these materials are listed in Table 2.
Table. 1 Standard of Common Raw Materials for Carbon Steel Pipe Fittings

Table. 2 Chemical composition and mechanical properties (reference values) of common raw materials for pipe fittings)

2. WPB Materials Overview

WPB material is the most commonly used carbon steel pipe connecting material at medium and high temperatures. It can be made from steel tubes like ASTM A106 GR.C or steel plates like ASTM A285 GR.C. The main chemical compositions and mechanical properties of the standard's requirements are presented in Table 3.

Table 3: Chemical composition and performance index of WPB (standard value)

3. The actual supply parameters of domestic S carbon steel material

The actual delivery values ​​of seamless steel pipes (GB 8163-20#) from Baosteel, Chengdu Seamless and Baotou and medium thickness hot-rolled carbon steel plates (GB 3274-Q235A/B) from Wuhan Iron and Steel Co ., Ltd. and Nanjing Iron and Steel Co., Ltd. are analyzed statistically. Specific statistical results are shown in Table 4.

Table 4 Statistics of chemical composition and properties of various common seamless steel tubes and plates (delivery value)

Note: The symbolic meaning and unit in the table are the same as in Table 2 and Table 3.

4. Comparison of domestic carbon steel materials with WPB

Tables 2 and 3 list the main chemical composition requirements and mechanical performance indicators for national carbon steel. Materials and WPB. This data covers the main requirements for standard materials for carbon steel pipe fittings. In other words, under current international and national metallurgical conditions, as long as the requirements in Tables 2 and 3 are met, the material properties can be considered as meeting the requirements of the relevant standards (some additional requirements not listed in the table are considered 100% compatible) . At the same time, it can also be assumed that the remaining requirements between domestic and foreign materials can be considered consistent, except for the points listed in Table 2 and Table 3, and no comparison is made here.

4.1 Comparison between standard value and standard value

(1) Comparison of chemical composition
Table 2 and Table 3 show that the C content of domestic materials is 0.12-0.24%, which fully meets the requirements of WPB C ≤ 0.3%. The Mn content of domestic raw materials is 0.35-0.70%, which fully meets the requirements of WPB Mn0.29-1.06%. The P and S content of domestic raw materials is ≤ 0.045%, which also fully meets the requirements of WPB P ≤ 0.05% and S ≤ 0.058%. The Si content of national raw materials 20# and 20G fully meets the requirements of WPB.
The Si content in Q235A and Q235B is not the same as that in WPB, but from Table 4 it can be seen that the Si content in Q235A and Q235B is between 0.16 and 0.22% in the actual delivery value. Therefore, the Si content of the supplied materials Q235A and Q235B also corresponds to that of WPB.
From the above, it can be seen that: In terms of standard specifications, domestic 20# and 20G carbon steel materials are fully consistent with WPB in chemical composition. Q235A and Q235B are also consistent with WPB except for Si, and it can be selectively guaranteed that the actual delivery value of Si content is consistent with WPB.
(2) Comparison of performance indicators
From the above, it can be seen that although the two types of materials may be consistent in terms of chemical composition requirements, the actual supply value of carbon content in domestic carbon steel materials (0.13-0.22% ) is obviously in the lower limit of 40 required by the WPB 0.30% (although it is within the required range), which directly leads to the lower limit of the strength requirements of national materials being lower than that of the WPB in terms of standard requirements. From Table 2 and Table 3, it can be seen that except for 20G, the lower limit of tensile strength of domestic materials is 375 – 410 MPa and the lower limit of yield strength is 235 MPa, which is below the requirements of 415 MPa specified in the WPB standard or 240 MPa. At the same time, in terms of material plasticity index, the standard elongation requirement (E%) for domestic materials (≥20-26%) is also due to the fact that the carbon content in domestic materials is below the requirement of the WPB and therefore be significantly higher than the standard WPB index (≥ 20%).
From the above, it can be seen that the requirements for domestic carbon steel materials in terms of performance indicators in terms of standard specifications are lower than the requirements for WPB. For this reason, it is also believed that domestic carbon steel materials cannot replace the use of WPB in many design projects.
In summary, from the comparison of standard specifications, it can be concluded that the chemical composition of domestic 20#, 20G, Q235A, 0235B and WPB carbon steel materials is the same (the Si content in 0 series steel needs to be selected). The performance index is lower than the WPB requirements.

4.2 Comparison of the national materials supply index value with the WPB standard value

Although domestic materials cannot replace WPB from a standard perspective, we can still draw some conclusions about practical substitution value from analyzing the real value of domestic materials supply. From the previous analysis, there are two main aspects that influence the determination of replacement:
(1) Si content in Q series steel plates;
(2) The standard performance indexes of all national materials are below the standard requirements of the WPB.
Comparing Table 3 and Table 4, we can see that:

• 1) The delivery values ​​of Si content in Q series steel plates are between 0.13% and 0.22%, which meets the requirements of WPB SI ≥ 0.1%.
• 2) The performance index of 20# and 20G grade steel pipes made from domestic materials, the actual delivery value of Ts is 420-550MPa, Ys is 250-350MPa, elongation E is 24-38%, HB is 145 -185 (actual measurement, tube hardness and raw material hardness are the same), all measured values ​​of furnace performance resistance index meet the requirements of WPB standard.

(3) The actual delivery value Ts of Q235A and Q235B steel plates is 405-495MPa, of which only two heat quantities are less than 410MPa (below the requirements of WPB), accounting for 0.8% of the total heat quantities ; ys is 255-360 MPa, consistent with WPB requirements; elongation E is 25-37%, which meets the requirements of WPB. HB is 140-170 (according to actual measurement, the hardness of the tube is the same as that of the raw material), which meets the requirements of WPB.

5. Conclusion