This standard specifies the technical requirements, test methods, inspection rules, marking, packaging, transportation and storage of cone seal welded pipe joints. JB/T 6386-1992 Technical requirements for cone seal welded pipe joints JB/T6386-1992 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
JB/T 6386-1992
Technical Conditions for Cone Seal Welded Pipe Joints
Published on July 14, 1992
Implementation by the Ministry of Machinery and Electronics Industry of the People's Republic of China on July 1, 1993
Mechanical Industry Standard of the People's Republic of China
Technical Conditions for Cone Seal Welded Pipe Joints
1 Subject Content and Scope of Application
JB/T 63861992
This standard specifies the technical requirements, test methods, inspection rules, marking, packaging, transportation and storage of cone seal welded pipe joints. This standard applies to various cone seal welded pipe joints and related parts specified in JB/T6381~6385. 2
Cited Standards
GB 700
GB1184
GB1804
GB7038
GB7306
GB7307
Technical requirements
Thread finish, shoulder distance, undercut, chamferOrdinary thread
Ordinary thread
Basic dimensions
Tolerances and fits
Technical conditions for high-quality carbon structural steel
Carbon structural steel
Tolerances of form and position
Tolerances and fits
Limit deviations of dimensions without tolerances
Tolerances of fasteners
Bolts, screws and nuts
Rubber for sealing rings
Pipe threads sealed with threads
Pipe threads sealed with non-threaded pipes
The materials of the parts shall be as specified in Table 1.
Parts name
Joint body
Thin nut
Tensile strength
Recommended grades
35, 45
20, 35
Q235-A
In addition to the materials specified in Table 1, other materials can be selected according to requirements, which shall be agreed upon by the supplier and the buyer when placing an order. The material of the O-ring shall comply with the provisions of GB7038 unless otherwise specified. The thread finishing, backing groove and chamfer of the parts shall comply with the provisions of GB3. The surface of the parts is generally oxidized (blackened or bluish). If other surface treatments are required, they shall be agreed upon by the supplier and the buyer.
Threads on parts
Standard number approved by the Ministry of Machinery and Electronics Industry on July 14, 1992
GB 699
GB 699
Implementation on July 1, 1993
JB/T6386-1992
3.3.1 The basic dimensions of common threads shall be in accordance with GB196, and the tolerances shall be in accordance with GB197. The internal thread is 6H and the external thread is 6g. 55 The external cylindrical pipe thread (G) with no thread seal shall be in accordance with Class A of GB7307. 55° The taper pipe thread (R) with thread seal shall be in accordance with GB7306.
3.3.2 The surface roughness parameter R of the external thread side is 3.2μm, and the surface roughness parameter R of the internal thread side is 6.3μm. 3.4 There are no cracks, pores, sand holes, burrs, flash, dents, scratches or defects that affect the use of the parts. 3.5 The shape and position tolerances of the hexagonal head of the parts shall comply with the product grade A regulations in GB3103.1. 3.6 The coaxiality tolerance between the axis of the 24° inner cone of the joint body and the axis of the tightening thread, and the coaxiality tolerance between the 24° outer cone of the tapered tube and the axis of its pipe diameter are both 0.1mm.
3.7 The verticality tolerance between the end face of the hexagonal head support surface of the joint body equipped with a combined washer or "0" type sealing ring and the thread axis is 0.1mm. 3.8 For the tapered tubes of JB6381~6385, the verticality tolerance between the axis after bending and the axis of the outer cone is 0.3mm. 3.9 Limit deviations of unmarked tolerance dimensions and unmarked shape and position tolerances of parts 3.9.1 Limit deviations of unmarked dimension tolerances of metal cutting parts on parts shall comply with GB1804, with holes being H13, shafts being h12, and length dimensions being Js13 or js13.
3.9.2 Unmarked shape and position tolerances of parts shall comply with Class C in GB1184. ) Parts shall be marked according to the type and specification. 3.10
Marks shall be marked on the S surface according to Figures 1 and 2. Figure 1
4 Test method
At an ambient temperature of 20~35℃, when the viscosity grade of the test oil is N32 (i.e., the viscosity is 28.8~35.2mm2/s at 40℃), the finished pipe joints are subjected to the following tests:
4.1 Static pressure test: When the finished pipe joints are pressurized to 1.5 times the nominal pressure, the pressure is maintained for not less than 5 minutes, and leakage is not allowed. 4.2 Pressure pulse test: The finished pipe joints are installed in the test device, and the pressure pulse waveform is tested at a frequency of 0.5~1Hz (30~60 times/min) for 100,000 times. There should be no leakage, and the parts should be checked after disassembly without damage. 5 Inspection rules
5.1 The finished pipe joints shall be inspected by the technical inspection department of the manufacturer in accordance with the construction drawings approved by the prescribed procedures and the relevant provisions of this standard, and the product quality certificate shall be filled in. 5.2 Sampling inspection method for pipe joints
5.2.1 When the ordering unit deems it necessary, it may conduct sampling inspection on the products delivered by the manufacturer according to this rule to determine whether the batch of products delivered is qualified, so as to determine whether to accept or reject. The inspection items are mainly technical requirements such as size and working performance. 5.2.2 Sampling inspection method
This rule adopts the counting sampling method, including primary sampling and secondary sampling. 5.2.3 Sampling plan table
JB/T 6386-1992
The batch range of each inspection item and the corresponding sampling plan are shown in Table 2. Table 2
Acceptance level
Inspection items
Appearance and main dimensions
(calculated as defective product rate)
Note: month,—number of first random inspections;bZxz.net
n2——number of second random inspections;
A,——number of first qualified judgments;
R,——number of first unqualified judgments;
A—number of second qualified judgments;
R—number of second unqualified judgments Number,
Inspection procedures for single sampling plan
Batch range
(pieces)
≤1000
>1000~3000
>3000~10000
>10000
Sample size
Judgment number
Randomly select a sample (n) from the batch, and judge whether the batch is qualified based on the inspection results of the sample. If the number of unqualified pieces in the sample (d) is less than or equal to the specified qualified judgment number (d≤A), then this batch of products is a qualified batch and can be accepted; if the number of unqualified products in the sample is greater than or equal to the unqualified judgment number (d>R.), then this batch is an unqualified batch and is rejected. 5 Inspection procedures for secondary sampling plan
First, randomly select the first sample from the batch (unit product number n,). Determine whether the batch is qualified based on the inspection result of the first sample, or conduct a second inspection. If the number of unqualified pieces in the sample (d,) is less than or equal to the first qualified judgment number (d≤A), then the batch is a qualified batch and can be accepted. If the number of unqualified pieces is greater than or equal to the first unqualified judgment number (d≥R,), then the batch is an unqualified batch and is rejected. If the number of unqualified pieces is between the qualified judgment number and the unqualified judgment number (A,
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