This standard specifies the terms, symbols, basic tooth profiles and dimensions of conical threads and cylindrical threads for gas cylinders. This standard applies to conical threads for connecting the mouth of gas cylinders to the valve and other sealed connections, and non-threaded sealed cylindrical pipe threads for connecting the cap and the collar. The conical threads for connecting the fusible plug and the plug seat of gas cylinders with safety devices can also be used with reference to this standard. GB 8335-1998 Special threads for gas cylinders GB8335-1998 Standard download decompression password: www.bzxz.net

GB8335-1998
This standard applies to the conical threads for connecting the mouth of the gas cylinder with the bottle valve and other sealed connections, and the cylindrical pipe threads for connecting the bottle cap with the neck ring.
Compared with the original GB8335-87 standard, this standard deletes the PZ30.3 conical thread specification; and adds three specifications of threads: Rc1/4/R1/4; Rc1/8/R1/8 and M85×16 (P4). The first two specifications of threads are only applicable to the connection between the fusible plug of the acetylene cylinder and the bottle, and the M85×16 (P4) multi-thread thread is only applicable to the connection between the neck ring of the welded gas cylinder and the bottle cap. This standard increases the comprehensive deviation of the median diameter of the conical thread from the original ±0.18 to +0.18 for the conical external thread and _.1 for the conical internal thread. In addition, necessary modifications have been made to the arrangement and text of the chapters. This standard replaces the entire content of the original GB8335-87. This standard shall be implemented from October 1, 1998.
This standard is proposed by the Ministry of Labor of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee for Standardization of Gas Cylinders. The drafting units of this standard are Shanghai Tianhai Valve Co., Ltd. and Shanghai High Pressure Vessel Factory. The main drafters of this standard are Cai Yanxin, Mao Chongni, Chen Weiming, Gu Yongliang and Hu Jinggan. 537
1 Scope
National Standard of the People's Republic of China
Special threads for gas cylinders
Special threads for gas cylinders This standard specifies the terms, symbols, basic tooth profiles and dimensions of tapered threads and cylindrical threads for gas cylinders. GB 8335—1998
Replaces GB8335—87
This standard applies to tapered threads for connecting the mouth of gas cylinders with cylinder valves and other sealed connections (hereinafter referred to as tapered threads) and cylindrical pipe threads for connecting caps with neck rings without thread sealing (hereinafter referred to as cylindrical threads). The conical thread connecting the fusible plug and the plug seat of the gas cylinder with safety device can also refer to this standard for use. 2 Reference standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and the parties using this standard should explore the possibility of using the latest versions of the following standards. GB192-81 Basic tooth form of common thread
GB196--81 Basic size of common thread (diameter 1~600mm) GB197--83 Tolerance and fit of common thread (diameter 1~355mm) GB3505--83 Surface roughness term surface and its parameters GB7306-87 Pipe thread for thread sealing ZBJ42037-89 Pipe thread gauge for thread sealing 3 Terms and symbols
3.1 Terms
3.1.1 Datum plane
The plane with the datum diameter perpendicular to the thread axis is referred to as the base plane. Note: For internal threads, it is the large end plane; for external threads, it is the plane whose distance to the small end is equal to the reference distance. 3.1.2 Reference diameter
The basic major diameter of internal or external threads.
3.1.3 Pitch of tapered thread
The distance between two points corresponding to adjacent teeth on the median diameter line parallel to the generatrix of the cone. 3.1.4 The median diameter deviation of tapered thread
is the comprehensive deviation of the median diameter including the deviation of the median diameter itself and the radial compensation value of the median diameter caused by the deviation of the tooth profile half angle, pitch deviation, cone angle deviation, etc.
3.1.5 Reference distance
The distance from the reference plane to the small end of the tapered external thread, referred to as the base distance. 3.1.6 Reference surface
The small end face of the external tapered thread (visible plane for inspection) The large end face of the internal tapered thread (visible plane for inspection). 558 approved by the State Bureau of Technical Supervision on March 20, 1998
implemented on October 1, 1998
3.2 Symbols
Dz(d2)-
major thread diameter;
-middle thread diameter;
minor thread diameter;
Dr(d,)-
conical thread of gas cylinder;
cylindrical thread of gas cylinder;
number of threads per 25.4mm;||t t||Pitch;
Base distance;
Effective length of tapered external thread;
Effective length of tapered internal thread;
4 Tapered thread
Original triangle height;bzxz.net
Tooth profile height (h—2hl=2hz);
Arc radius;
Tooth profile angle;
Tooth profile half-angle deviation;
Inclination angle;
Inclination angle deviation;
Taper.
4.1 Basic tooth form and dimensions of tapered threads
GB 8335—1998
The basic tooth form and dimensions of tapered threads shall comply with the provisions of Figure 1 and Table 1. Base surface
External thread
H=0.960491P;r=0.137P;
h=0.640330P;K=3:25.
The bisector of the tooth form angle is perpendicular to the cone generatrix. 2 The top of the tooth form is allowed to be flat.
Internal thread
External thread
Parallel line of the thread axis
122.117|39.000
GB 8335—1998
Basic dimensions and deviations of thread
Diameter on base surface
Limit deviation
Limit deviation
Di(dt)
Limit deviation
Thread length
0.1826.636+0.18-0.1825.472+0.180.1817.6726221.1620.2491.81427.800+0.18—
4.2 Deviation of mean diameter of tapered thread
16.002219
The deviation of mean diameter of tapered thread is expressed by the axial variation base of the base surface position, and its variation range does not exceed 1.5mm. The deviation of the median diameter of the tapered external thread is +0.18mm, and the deviation of the median diameter of the tapered internal thread is -0.18mm. The tapered external thread is checked with a tapered thread ring gauge. The thread size of the large end of the ring gauge thread should be the same as the thread size on the base surface of the thread; the small end of the ring gauge thread is made with a step, the height of the step is 1.5mm, and the distance from the small end plane to the large end plane is equal to the base distance. When the ring gauge is screwed on the external thread, the small end plane of the external thread should be within the height range of the small end step of the ring gauge, as shown in Figure 2. 1.5mm
Internal threads are checked with a thread plug gauge. The large end of the plug gauge is made with a step, the height of the step is 1.5mm, the thread size of the large end of the step should be the same as the thread size on the base surface of the thread, and the distance from the large end of the step to the small end plane is equal to the base distance. When the plug gauge is screwed into the internal thread, the end face of the screw hole should be within the height range of the step, as shown in Figure 3. L
4.3 The deviation of the distance between the crest and the root of the tapered thread and the thread median diameter shall be in accordance with the provisions of Figure 4, that is, the deviation of the thread crest (h for tapered external thread, h2 for tapered internal thread) is taken as -0.025mm, and hz is taken as +0.025mm; the deviation of the thread root (hz for tapered external thread, h1 for tapered internal thread) is taken as ±0.025mm. S20-0-
Tapered external thread
Tapered internal thread
Thread median diameter
4.4 The tooth profile half angle deviation, inclination angle deviation and pitch deviation shall be in accordance with the provisions of Table 2. Table 2 Deviation of half angle, inclination angle and pitch of thread Ag
Tapered external thread
+10″
Tapered internal thread
In length
In length Lz and L
4.5 Deviations in 4.3 and 4.4 of this standard shall be used as the basis for designing tools for tapered threads. 4.6 The connection between the fusible plug of dissolved acetylene gas cylinder and the cylinder is allowed to adopt two specifications, Rc1/4/R1/4 and Rc1/8/R1/8. Their accuracy and dimensions shall comply with the provisions of GB7306; the inspection gauge shall comply with the provisions of ZBJ42037. 4.7 If necessary, the supply and demand parties may agree to increase the inspection of individual elements to improve the quality of the thread. 4.8 The surface roughness of the tapered thread profile shall be in accordance with GB 3505 5 Cylindrical thread
1 The basic tooth shape and dimensions of PG80 cylindrical thread shall comply with the provisions of Figure 5 and Table 3. 5.1
('p)\a
H=0.960491P
h-0.640330P
r=0.137320P
GB83351998
Table 3 Basic dimensions of PG80 cylindrical thread
The limit deviation of PG80 cylindrical thread shall comply with the provisions of Figure 6 and Table 4. 5.2
PG80 cylindrical thread limit deviation
Thread category
Thread diameter
Limit deviation
Bottle cap (collar)
Dz(d2)
5.3For welding gas cylinder caps (cylinders with large protective covers)) and bottlenecks, M85×16 (P4) multi-thread threads are used. 5.4For liquefied petroleum gas cylinder caps and bottlenecks, M80×3 specification threads are used and comply with the provisions of GB192, GB196, and GB197. 562
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