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This standard is prepared in accordance with the rules given in GB/T 1.1-2009.
This standard replaces JB/T 6374-2006 Specifications for silicon carbide rings of mechanical seal, and the following technical changes have been made with respect to JB/T 6374-2006:
——The normative references have been modified (see Clause 2; Clause 2 of Edition 2006);
——The variety of sealing rings has been added, and the codes of each variety have been uniformly changed into international common symbols (see Table 1; Table 1 of Edition 2006);
——The performance indexes such as bulk density, bending strength, compressive strength, elastic modulus, coefficient of linear expansion and thermal conductivity have been improved (see Table 2; Table 2 of Edition 2006);
——The purity of silicon carbide raw material in the composition of sealing ring has been improved (see Table 4; Table 4 of Edition 2006);
——Requirements for the sealing end face quality have been improved (see 4.4; 4.4 of Edition 2006);
——The bulk density test method has been modified (see 5.1; 5.1 of Edition 2006);
——Optical microscope detection method for surface defects has been added (see 5.9; 5.9 of Edition 2006);
——The test method of thermal conductivity has been modified (see 5.13; 5.13 of Edition 2006);
——The inspection rules have been modified (see Clause 6; Clause 6 of Edition 2006).
This standard was proposed by the China Machinery Industry Federation.
This standard is under the jurisdiction of the SAC/TC 491 National Technical Committee on Mechanical Seal of Standardization Administration of China.
The previous editions of the standard are as follows:
——JB/T 6374-1992, JB/T 6374-2006.
Silicon carbide rings of mechanical seal—Specification
1 Scope
This standard specifies the product classification, technical requirements, test and inspection methods, inspection rules, marking, packaging, transportation and storage of silicon carbide rings of mechanical seal.
This standard is applicable to sealing rings for mechanical seal made of reaction-bonded silicon carbide, pressureless sintered silicon carbide (solid phase, liquid phase, graphite added or seal end face containing micropores) and hot pressed sintered silicon carbide (hereinafter referred to as sealing rings).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced documents (including any amendments) applies.
GB/T 191 Packaging—Pictorial marking for handling of goods
GB/T 1184-1996 Geometrical tolerancing—Geometrical tolerances for features without individual tolerance indications
GB/T 2828.1-2012 Sampling procedures for inspection by attributes—Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection
GB/T 3045 Conventional abrasive—Chemical analysis of silicon carbide
GB/T 6569 Fine ceramics (advanced ceramics, advanced technical ceramics)—Test method for flexural strength of monolithic ceramics at room temperature
GB/T 8489 Test method for compressive strength of fine ceramics (advanced ceramics, advanced technical ceramics)
GB/T 10700 Test method for elastic moduli of fine ceramics (advanced ceramics, advanced technical ceramics)—Bending method
GB/T 16534 Fine ceramics (advanced ceramics, advanced technical ceramics)—Test method for hardness of monolithic ceramics at room temperature
GB/T 16535 Fine ceramics (advanced ceramics, advanced technical ceramics)—Test method for linear thermal expansion of monolithic ceramics by push-rod technique
GB/T 22588 Determination of thermal diffusivity or thermal conductivity by the flash method
GB/T 25995 Test method for density and apparent porosity of fine ceramics
3 Product classification
See Table 1 for classification and code of sealing rings manufactured according to different processes.
Table 1
Category of sealing ring Reaction-bonded silicon carbide Pressureless sintered silicon carbide Hot-pressing sintered silicon carbide
Code RBSiC SSiC LPSSiC SSiC-G SSiC-P HPSiC
SSiC stands for solid-phase sintered silicon carbide with boron and boride added; LPSSiC stands for liquid-phase sintered silicon carbide with alumina and yttrium oxide (YAG) added; SSiC-G stands for silicon carbide-graphite material mixing silicon carbide with graphite; SSiC-P stands for a silicon carbide material with micropores on the sealing end face.
4 Technical requirements
4.1 The performance of various sealing rings shall be in accordance with those specified in Table 2.
Table 2
Item Unit Category
RBSiC SSiC LPSSiC SSiC-G SSiC-P HPSiC
Bulk density g/cm3 ≥3.05 ≥3.10 ≥3.20 ≥2.80 ≥2.90 ≥3.15
Porosity % - - - - 4~10 -
Surface pore size μm - - - - 30~80 -
Hardness HV0.5 - ≥2,200 ≥2,200 ≥2,000 ≥2,200 ≥2,500
HRA ≥90 ≥92 ≥92 - - ≥92
Bending strength (three-point method) MPa ≥350 ≥400 ≥500 ≥200 ≥230 ≥550
Compressive strength NPa ≥2,000 ≥2,000 ≥2,200 ≥1,000 ≥2,000 ≥2,200
Elastic modulus GPa ≥350 ≥380 ≥420 ≥200 ≥350 ≥410
Linear expansion coefficient (0°C~1,000°C) 10-6°C-1 ≥4.0 ≥4.0 4.0~5.0 3.0~5.0 4.0~5.0 4.0
Thermal conductivity (room temperature) W/(m·K) 50~100 90~110 60~90 90~130 90~110 110
4.2 The surface porosity defects of the sealing ring shall be in accordance with those specified in Table 3 (except SSiC-P).
Table 3
End face area of sealing ring
cm2 Maximum number of pores allowed Pore size
mm
≤5 1 <0.1
5~10 2
10~30 3
>30 5
4.3 The composition of each type of sealing ring shall be in accordance with those specified in Table 4.
Table 4
Category Composition Free silicon content (mass fraction)% Purity of silicon carbide raw material (mass fraction)%
RBSiC SiC, Si, C <12 ≥98.5
SSiC SiC, B4C, C -
LPSSiC SiC, YAG
SSiC-G SiC, graphite
SSiC-P SiC, B4C, C
HPSiC SiC, B4C, C
4.4 The sealing ring shall be free from cracks and other defects affecting the service performance, and the sealing end face of the sealing ring shall be free of scratches and inclusions. There shall be no visible free silicon aggregation on the sealing end face of RBSiC or pore aggregation on the sealing end face of SSiC-P.
4.5 The flatness error of the sealing end face of sealing ring shall not be greater than 0.0009 mm, and the surface roughness Ra shall not be greater than 0.2 μm.
4.6 The surface roughness Ra of the contact part between the sealing ring and the auxiliary sealing ring shall not exceed 1.6 μm.
4.7 The parallelism between the sealing end face of the sealing ring and the end face of the auxiliary sealing ring shall meet the grade of tolerance 7 specified in GB/T 1184-1996.
4.8 The perpendicularity of the sealing end face of the sealing ring to the outer circle or inner bore in contact with the auxiliary sealing ring shall meet the grade of tolerance 7 specified in GB/T 1184-1996.
4.9 Dimensional tolerance zones for the outer circle or inner bore contacted by the sealing ring and the auxiliary sealing ring shall be h7 or H7.
Foreword i
1 Scope
2 Normative references
3 Product classification
4 Technical requirements
5 Methods for test and inspection
6 Inspection rules
6.1 Inspection classification
6.2 End-of-manufacturing inspection
6.3 Appraisal inspection
7 Marking, packaging, transportation and storage
Bibliography
