JB/T 6539-1992Steel pressure vessels for miniature air compressors (English PDF)

3.1 Working pressure

It refers to the gauge pressure in the pressure vessels under normal operating conditions.

3.2 Rated working pressure

It refers to the pressure specified by the pressure vessel model, whose value is equal to that of the rated exhaust pressure of compressors.

3.3 Maximum working pressure

It refers to the maximum gauge pressure that might achieve in the pressure vessels under normal operating conditions.

3.4 Design pressure

It refers to the pressure used for determining the wall thickness of pressure vessels, which is 1.05 to 1.1 times the value of the rated working pressure.

However, the design pressure shall not be lower than the maximum working […]

4.1 Designated Scope

The scope of pressure vessels designated in this Standard is as follows:

4.1.1

The first flange sealing surface of the connecting tube.

4.1.2

The first screwed connection of the connecting tube.

4.1.3

The first circumferential weld of the connecting tube.

4.1.4

The pressure control and safety relief devices and meters directly installed on the pressure vessels shall conform to the relevant provisions of this Standard.

4.2 Allowable stress

Each intensity data of steels and bolts is respectively divided by the safety factors, given in Tables 1 and 2. TAKE the smaller value.

Table 1

Intensity Performance

Minimum Tensile Strength at

Room Temperature sigmab

Yield Point at Room Temperature or Design Temperature sigmas or sigma t s

Carbon Steel & Low Alloy Steel

Safety Factor n >= 3.0 ns >= 1.6

Table 2

Steel Bolt Diameter mm

Heat Treatment

Conditions

Safety Factor of Yield

Point at Design

Temperature ns

Carbon Steel

<= M22 Hot Rolling &

Normalizing

2.7 M22~M48 2.5

Low Alloy Steel &

Alloy Steel

<= M22

Normalizing &

Hardening and

Tempering

3.5 M22~M48 3.0

5.2 Pressure parameters

The rated working pressure of pressure vessels shall be selected according to Table 3.

Table 3 MPa

0.25 0.4 0.5 0.7 1.0 1.25 1.4

5.3 Cylinder diameter

5.3.1

When using steel plates to rolling cylinders, the nominal diameter shall be selected according to Table 4. At this moment, the nominal diameter of cylinders refers to the inner diameter of cylinders.

Table 4 mm

150 200 250 300 350 400 450 500 550 5.3.2 When using steel pipes as cylinders, the nominal diameter of cylinders shall be selected according to GB 8163. At this moment, the nominal diameter of cylinders refers to the outer diameter of steel pipes.

6.1 General requirements

6.1.1

The steel plates and pipes used for manufacturing the pressure vessels shall have material certificates (or copies). The manufacturing organizations shall perform acceptance according to the certificates.

6.1.2

The steels for pressure parts of pressure vessels shall conform to the provisions specified in this Chapter. For other materials, if their performance is not worse than the material performance specified in this Chapter, it is allowable to be used for substitute.

6.1.3

The steels and corresponding welding materials listed in this Chapter shall also meet the requirements of corresponding standards.

6.2 Steel plates

6.2.1

When using the boiling carbon steel plates and killed carbon steel plates for manufacturing pressure vessels, the scope shall conform to the provisions specified in Table 5.

6.4 Bolts

The steel designation and allowable stress of bolts shall conform to the provisions specified in Table 8.

Table 8

Steel designation

Steel

Plate

Standard

Using Status

Bolt

Specifications mm

Strength Index at

Room Temperature

Allowable Stress at the

Following Temperatures (°C)

MPa

sigmab

MPa

sigmas

MPa

<= 20 100 150 200

Carbon Steel Bolts

Q235-A (A3, AY3)

GB 700 Hot Rolling < M24 370 235 87 78 74 69

6.5 Welding materials

6.5.1

The recommended welding materials for pressure vessels are given in

Table 9.

6.5.2

If using the materials of different steel designations for welding, the welding materials shall be determined by test, or shall conform to the provisions of relevant welding procedure regulations and standards.

Table 9

Steel

Designation

Arc Welding Submerged Arc Welding

Steel

Designation of Welding

Wires for

Carbon

Dioxide

Gas-shielded

Arc Welding

Steel designation of Welding

Wires for

Argon Arc

Welding

Welding

Rod

Model

Corresponding

Trademark

Example

Steel

Designation of Welding

Wires

Welding Flux

Model

Corresponding

Trademark

Example

Q-235-A, F (A3F)

E4303 J422

H08

H08Mn

HJ401-H08A HJ431 H08Mn2Si -

Q-235-A (A3)

Q-235-B,

10

Q-235-C,

20

20g, 20R,

20HP

E4316 J426 H08A

H08MnA

HJ401-H08A HJ431 H08Mn2Si -

E4315 J427

16MnR E5016 J506 H10MnS

H10Mn2

HJ402-H10Mn2 HJ350

H08Mn2SiA H10Mn2

16Mn E5003 J502 HJ401-H08A HJ431

7.1 Symbol instructions

Di - Inner diameter of cylinders or heads, mm;

hi - Depth of head curve surface, mm;

K - Shape factor of ellipsoidal heads;

M - Shape factor of dished heads;

p - Design pressure, MPa;

[p] - Allowable pressure, MPa;

Ri - Inner radius of spherical parts of dished heads, mm;

r - Inner radius of transition corners of dished heads, mm;

delta - Calculated thickness of cylinders or heads, mm;

deltae - Effective thickness of cylinders or heads, mm;

8.2 General provisions of openings

8.2.1

The openings on the cylinders and heads shall be round and

ellipsoidal. When the openings are ellipsoidal, the ratio of long diameter to short diameter of the opening shall not be greater than 2.

8.2.2

All of the openings shall keep away from butt weld-seams. The distance between opening edge and weld-seam shall not be less than 50mm.

8.2.3

For the pressure vessels using compressed air as working medium, when the corrosion allowance is within the range of 0.5mm ~ 1.0mm, it is allowable to have no additional inspection openings.

8.3

Provisions on the permission of no additional opening reinforcement

8.3.1

The space between the centers of two adjacent openings is 1.5 times the sum of two opening diameters and above.

8.3.2

Full penetration welding shall be applied to the connecting tubes.

8.3.3

When the nominal wall thickness of the connecting tubes or screwed connections is not less than that of the shells, the opening diameter shall not be greater than 40mm; when the nominal wall thickness of the connecting tubes or screwed connections is not less than 1.3 times the nominal wall thickness of the shells, the opening diameter shall not be greater than 60mm.

8.4 Opening reinforcement

8.4.1 Allowable opening range

a. The maximum diameter of the openings on the cylinders and heads d shall be <= 0.5Di.;

b. For the openings on the transition positions of ellipsoidal or dished heads, the projection distance between the opening edges or between the edge of the additional reinforcing element and the head edge shall not be less than 0.1Di.

8.4.2 Reinforcing structure

a. Pad reinforcement: USE full penetration weld-seam process or basic penetration weld-seam process to weld the reinforcing parts with the connecting tubes and shells. The design for opening reinforcement shall be executed according to Article 8.5;

b. Thick-walled tube reinforcement: INCREASE the wall thickness of connecting tubes. USE full penetration weld-seam process or basic penetration weld-seam process to weld the connecting tubes with the shells. The design for opening reinforcement shall be executed according to Article 8.5.

8.5 Reinforcement calculation

8.5.1 Reinforcement area required for opening

The reinforcement area, required in the longitudinal section, passing through the opening center and the shell axis, shall be determined according to the following requirements:

8.5.1.1

The cylinders shall be calculated according to the Formula (9).

Where:

delta - Calculated wall thickness, mm. The calculated wall thickness shall be calculated according to the Formula (3).

9.1.2

The supporting seats or hanging seats can be applied to the vertical

pressure vessels for support. The seats shall conform to the provisions specified in relevant standards or drawings.

9.1.3

The distance between shell support and shell longitudinal weld-seam shall not be less than 50mm.

9.1.4

The connecting weld-seams between supports and shells shall have smooth transition.

9.2 Plates

9.2.1

The distance between the connecting weld-seams and the circumferential weld-seams of host plates, motor plates, and shells shall not be less than Di /4.

9.2.2

The distance between the connecting weld-seams of host plates, motor plates, and shells and the longitudinal weld-seams of shells shall not be less than 50mm.

9.2.3

The connecting weld-seams between plates and shells shall have smooth transition.

9.2.4

The upper surfaces of plates shall keep level.

10.1 General provisions

10.1.1

The manufacturing, inspection and acceptance of pressure vessels shall not only conform to the relevant provisions of this Standard, but also meet the requirements of design drawings.

10.1.2

The welding of pressure vessels must be conducted by the welders with the corresponding categories of welding certificates issued by the labor department.

The flaw detection of pressure vessels must be conducted by the personnel with the corresponding qualification certificates of flaw detection method issued by the labor department.

10.1.3 The manufacturing quality management system of pressure vessels

10.3.4 Weld-seam maintenance

10.3.4.1

When it is necessary to conduct weld-seam maintenance, the

maintenance process shall conform to the provisions specified in the Article

10.3.2.

10.3.4.2

The same weld-seam position should not be maintained more than twice. If being maintained more than twice, the maintenance shall be approved by the technical director of the organization. The maintenance times, positions and conditions shall be noted down in the quality certificate.

10.3.5 Welder steel seal

After welding, the welder steel seal shall be stamped on the specified location near the weld-seams.

10.4 Product test-plates

10.4.1

For the 10 sets in the first batch, it shall successively make the product test-plates. If all the test results for the product test-plates of 10 consecutive sets are qualified, after approved by the technical director of the organization, then the qualification of making one product test-plate for 20 sets in one batch can be obtained.

10.4.2

When making one product test-plate for 20 sets in one batch, and all the test results for the test-plates of 5 consecutive batches of pressure vessels are qualified, then the manufacturing organizations can submit application to the local supervision and inspection department for pressure vessels for the qualification of making one product test-plate for 50 sets in one batch.

10.4.3

In the process that making one product test-plate for 20 sets or 50 sets, as long as there is an unqualified result of one product test-plate, then the procedure described in the Articles 10.4.1 and 10.4.2 shall be repeated, so as to obtain the qualification of batch test-plate again.

10.4.4

For the batch test-plate making that is bases on a batch of 20 sets or

50 sets, it shall be specified by the inspection departments of manufacturing organizations, however, it shall be arranged on the first few sets as possible.

10.4.5

The product test-plates and the product materials shall have the same steel designation and specifications. The welding process which is the same as that of the pressure vessels shall be used on the extended positions of Class A weld-seams for pressure vessel shells. The welding of the product test-plate shall be conducted under the same welding conditions while welding the pressure vessel in the meantime.

10.4.6

The dimensions of the test-plate is 300mm × 250mm. The dimensions, cutting, test methods, and assessment requirements of test-plates shall conform to the relevant provisions specified in the Appendix

G of GB 150.

10.4.7

When the test results of the test-plate are determined to be unqualified, then it is allowable to double the sampling for re-inspecting the unqualified items, or to sample from this batch of products for re-inspection.

When the test results are still unqualified, then this batch of products represented by the test-plate shall be determined as unqualified.

10.5 Nondestructive inspection

10.5.1

After the weld-seams on the shells of pressure vessels pass the appearance inspection, the nondestructive inspection shall be conducted according to the requirements of drawings.

10.5.2

It is allowable to conduct local nondestructive inspection to Class A and B weld-seams for pressure vessel shells. Priority in local nondestructive inspection shall be given to the T-shaped weld-seam joints.

During the radiographic inspection, respectively TAKE a radiograph on Class

A weld-seams and two T-shaped joints. The radiograph shall not be less than

150mm in length.

During the ultrasonic inspection, the inspection length shall not be less than

20% of the length of each weld-seam.

10.5.3

The radiographic inspection for Class A and B weld-seams shall be conducted according to GB 3323, and can only be considered as qualified after achieving Level III.

10.5.4

The ultrasonic inspection for Class A and B weld-seams shall be conducted according to JB 1152, and can only be considered as qualified after achieving Level II.

10.5.5

For the Class A and B weld-seams conducted with local inspection, when discovering unallowable defects, the inspection length shall be increased on the extended position on both sides of the defect. The increased length shall be 10% of the weld-seam length, and shall not be less than

150mm. If the unallowable defects still exist, 100% inspection shall be conducted to this weld-seam.

10.5.6

For the Class A and B weld-seams with unallowable defects,

CONDUCT maintenance by welding after defect elimination. Furthermore,

USE the original inspection method to re-inspect the position, until it becomes qualified.

10.5.7

Other nondestructive inspections shall be conducted to pressure vessels according to the design drawings.

10.6 Pressure-withstand test

10.6.1

The hydrostatic test shall be conducted to the finished pressure vessels according to 1.5 times the design pressure. The hydrostatic test with specific requirements shall be conducted according to the design drawings.

10.6.2

During the hydrostatic test, the vessels shall be filled with water, and the air inside shall be exhausted. KEEP the outer surfaces of vessels dry during the test.

10.6.3

The hydrostatic test system shall be equipped with two pressure gauges with the same range and within the validity period of verification. The range of pressure gauges is better to be about 2 times the test pressure.

10.6.4

The pressure shall rise slowly during the test. KEEP the pressure for at least 10min after reaching to the test pressure. REDUCE to design pressure afterwards. CHECK each weld-seam and connecting position.

There shall be no leakage or other abnormalities.

10.6.5

The water temperature shall not be lower than 5°C during the hydrostatic test.

10.6.6

After the hydrostatic test, DRAIN the water in the vessels in time, and

DRY the vessels afterwards.

10.7 Painting and marks

10.7.1

Before welding the inner surfaces, and after welding the outer surfaces of the shells of pressure vessels (only referred to the non-lubricated compressors), REMOVE the rust, oil, and other sewages, and PAINT the anti-rust primer.

10.7.2

The paint films of the finishing coat for pressure vessels shall be uniform without any air bubbles, cracks, detachment, or other defects.

10.7.3

The compressor models shall be marked on the sides of pressure vessels in striking color.

10.7.4

The paint requirements for pressure vessels shall conform to the provisions specified in the JB 2536.

10.8 Exit-factory files and nameplates

10.8.1

The exit-factory files of pressure vessels shall include:

10.8.1.1 Certificate of quality

The certificate of quality shall meet the relevant requirements specified in the

Safety Technical Supervision Regulations for Pressure Vessels.

10.8.1.2

Completion drawings, whose contents are as follows:

a. Technical characteristics;

b. Table for major parts and components.

The completion drawings of the products with same specifications can be unifiedly printed.

10.8.1.3 Product quality certificate

The product quality certificate shall be stamped with the seal of the Pressure

Vessel Supervision and Inspection Department.

10.8.2

The nameplate shall include the following contents:

a. Vessel name and classification;

b. Name of manufacturing organization, and license number;

c. Design pressure, MPa; design temperature, °C;

d. Test pressure and maximum allowable working pressure, MPa;

e. Weight of the pressure vessel, kg;

f. Manufacturing date and product number;

g. Mark of the Pressure Vessel Supervision and Inspection Department.

11.1 Safety valve

The pressure vessels shall be equipped with overpressure discharge devices

- safety valve.

11.1.1

The safety valves shall meet the requirements specified in the JB/T 6441.

11.1.2

The design pressure of pressure vessels shall not be less than the opening pressure of safety valves. During the full discharge of safety valves, the pressure increment in the pressure vessels shall not exceed 10% of the design pressure.

11.1.3

The rated discharge capacity of safety valves shall not be less than the safe discharge capacity of pressure vessels.

11.1.4

The opening deviation of safety valves shall meet the following requirements:

a. When the relieving pressure is less than or equal to 0.48MPa, the opening pressure deviation is ± 0.013MPa.

b. When the relieving pressure is greater than 0.48MPa, the opening pressure deviation shall not exceed 3%.

11.1.5

The safety valves shall be installed vertically. For the through-holes on the connecting tubes between pressure vessels and safety valves, the cross-sectional area shall not be less than the inlet area of safety valves.

11.2 Pressure gauge

11.2.1

The pressure gauges shall be installed on the positions of pressure vessels which are easy for observation.

11.2.2

The scale values on the pressure gauge plates shall not be less than 1.5 to 3.0 times the maximum working pressure.

11.2.3

The diameter of pressure gauge plates shall not be less than 40mm.

11.3 Drain valve

11.3.1

The drain valves shall be installed at the lowest positions of pressure vessels.

11.3.2

The drain valves shall conform to the provisions specified in the drawings and relevant technical documents.

____________________

Additional information:

This Standard was proposed by National Technical Committee of

Standardization for Compressors.

This Standard shall be under the jurisdiction of the Hefei General Machinery

Research Institute of the Ministry of Machinery and Electronics Industry.

The Hefei General Machinery Research Institute of the Ministry of Machinery and Electronics Industry was responsible for drafting this Standard.

The main drafters of this Standard are Wu Ruyuan, Chen Fang, and Huang

Jijun.

__________ END __________ […]