1. Tees, crosses, press-formed reducers, and pipe caps formed by the direct cutting of bars of all material categories shall be non-destructively tested one by one; among them, carbon steel, alloy steel, and low-temperature steel shall be tested according to NB/T47013.4 or related specifications for magnetic particle testing, stainless steel category according to NB/T47013.5 or related specifications for penetration testing, Class I is qualified.
2. In addition to the varieties mentioned in 1, other steel pipe fittings of the alloy steel category (including steel pipe fittings of material grade LF450K3 and LF680K4 in the category of low-temperature steel) should be tested one by one according to NB/T47013.4 or related specifications, and grade I is qualified.
3. In addition to provision 5, when the weld seam of the welded steel pipe fitting is completed by the steel pipe fitting manufacturer, the full length of the weld seam of the welded steel pipe fitting should be inspected according to NB/T47013. Manufactured flanging nipples in the same way).
4. In addition to provision 5, for welded
steel pipe fittings made of straight seam welded pipes, if the weld seam has passed the radiographic inspection of the welded pipe manufacturer and is qualified for Class II, the weld seam of the steel pipe fittings can no longer be inspected by radiographs, but there are other requirements except. If the weld seam of the welded pipe has not been 100% radiographically inspected by the welded pipe manufacturer, the entire length of the weld seam of the welded steel pipe fittings should be inspected according to NB/T47013.2 or related specifications, and the grade II is qualified.
5. For welded steel pipe fittings that do not require welding seam radiographic inspection under the conditions of use, after negotiation between the supplier and the buyer, the weld seam may not need a radiographic inspection, but the suffix letter NX should be added after the material grade of the steel pipe fittings on the delivery documents and physical marks, such as CF370NX.
6. In addition to the above provisions, non-destructive testing can be carried out according to the content negotiated between the supplier and the buyer; for example, magnetic particles, penetrant and ultrasonic testing, etc. are required separately.
Relevant provisions in the national steel flange standard "GB/T9124-2010 Technical Conditions for Steel Pipe Flanges":
1. Low carbon steel and austenitic stainless steel forgings for steel flanges with a nominal pressure of PN2.5-PN16 and Class 150 are allowed to use Class I forgings (test hardness one by one).
2. If the following conditions are met, the forgings for steel flanges shall meet the requirements of forgings of grade III or above (sampling stretching and ultrasonic testing one by one):
a. Forgings for steel flanges with nominal pressure ≥ PN100 and ≥ Class 600;
b. Chromium-molybdenum steel forgings for steel flanges with nominal pressure ≥ PN63 and ≥ Class 300;
c. Ferrite forgings for steel flanges with nominal pressure ≥ PN25 and greater than or equal to Class ≥ 300 and working temperature ≤ -20°C.
3. Forgings for other steel flanges shall meet the requirements for forgings of Class II or above (sampling inspection).
