This standard specifies the requirements on the manufacturing, inspection and acceptance as well as marking, painting and packing of boiler header.
This standard is applicable to the stationary hot water boiler and the stationary steam boiler with the rated steam pressure no larger than 13.7MPa and the rated steam temperature no larger than 540℃, in addition, it is also usable to the subcritical pressure steam boiler.
2 Normative References
JB 1612 "Specification for Boiler Hydraulic Pressure Test"
JB/T 1613 "Specification for Welding of Boiler Pressure Parts"
JB/T 1615 "Specification for Painting and Packing of Boilers"
JB/T 1623 "Dimensional Deviation for Center-to-center Distance between Pipe Orifices of Boiler"
JB/T 1625 "Dimension of Welded Pipe Orifice of Middle and Low Pressure Boiler"
JB 3375 "Receiving Acceptance of Raw Materials for Boiler"
JB 4308 "Specification for Stamps and Marks Transferring of Boiler Products"
3 Technical Requirements
3.1 Materials and Welding
3.1.1 The materials for boiler header shall be adopted according to those specified in the related technical documents. The materials for manufacturing the boiler header shall be in accordance with the requirements of design pattern, and the substitute materials shall be examined and approved according to established procedures.
3.1.2 The steel products and welding materials for manufacturing the boiler header must pass the receiving acceptance conducted by the inspection department according to those specified in JB 3375, and those that have not conducted with the receiving acceptance or are rejected in the inspection are disallowed to be used in the production. The barrel body materials shall be marked and transferred according to those specified in JB 4308 after the cutting and laying off. And the barrel body must be stamped with the serial number of the receiving acceptance on materials.
3.1.3 The welding work of boiler header shall be in accordance with those specified in JB/T 1613.
3.2 Splicing
3.2.1 The length of the shortest barrel section of header barrel body shall be no less than 500mm.
3.2.2 As for the total splicing circumferential joints of header (excluding circumferential joints for design), when the header length L is no larger than 5m, the quantity of circumferential joints shall not exceed 1; when L is larger than 5m but no larger than 10m, the quantity of circumferential joints shall not exceed 2; and when L is larger than 10m, the quantity shall not exceed not exceed 3.
3.3 Connecting Pieces
The height of the pipe head on the boiler header shall not be less than 50mm for the hot water boiler and the steam boiler with the rated steam pressure no larger than 3.82MPa and shall not be less than 70mm for the steam boiler with the rated steam pressure larger than 3.82MPa.
3.4 Piercing and Welding Parts on Welded Seam
3.4.1 The welded pipe orifices of pipe head shall not the set on the welded seams and the connection welds of pipe head shall not be coincided with the heat-affected zone of the adjacent welded seam mutually as much as possible. If they can not be avoided, holes may be pierced on the welded seam or in its heat-affected zone, however, the following requirements shall be met at the same time:
a. The welded seams within a scope of 60mm (the diameter of the pipe orifice shall be taken when this diameter is larger than 60mm) around the pipe orifice shall be accepted in the radiographic inspection, and the welded seams at the margin of pipe orifice shall be free from entrapped slag;
b. The connection welds among pipe heads shall be relieved with the stress after the postweld heat treatment.
3.4.2 The distance from connection welds of support parts on the header to the splicing welds of header shall be larger than 100mm. It is to be avoided to weld the parts on welded seams or in the heat-affected zone. If it can not be avoided, the attachment weld of this part may pass through the welded seam but can not terminate on the welded seam or in the heat-affected zone in order to avoid stress concentration happening at these positions.
3.5 Heat Treatment
After completing the welding works (including the reworking) of boiler header, the heat treatment shall be carried out according to those specified in JB/T 1613.
