JB/T 6879-2021 English PDF (JBT6879-2021)

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JB/T 6879-2021: Dimensional tolerances of wet surfaces in the castings of centrifugal pumps
JB/T 6879-2021
JB
MACHINERY INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 23.080
J 71
Replacing JB/T 6879-2008
Dimensional Tolerances of Wet Surfaces in the Castings of
Centrifugal Pumps
ISSUED ON: DECEMBER 2, 2021
IMPLEMENTED ON: APRIL 1, 2022
Issued by: Ministry of Industry and Information Technology the People’s
Republic of China
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Basic Provisions ... 4
3 Technical Requirements ... 4
Foreword
This Standard was drafted as per the rules specified in GB/T 1.1-2009.
This Standard replaced JB/T 6879-2008 Dimensional Tolerances of Wet Surfaces in the
Castings of Centrifugal Pumps. Compared with JB/T 6879-2008, the major technical changes
of this Standard are as follows:
--- Modify the scope (see Clause 1 of this Edition; Clause 1 of the 2008 Edition);
--- Modify the dimensional tolerance requirements for the wet surfaces of castings produced
by precision casting method (see 3.1 of this Edition; 3.1 of the 2008 Edition);
--- Add the dimensional tolerance requirements for impellers and guide vanes produced by
ceramic casting method [see 3.1c) of this Edition];
--- Modify the dimensional limit deviations of the wet surfaces of impellers with Class-B
accuracy (see Table 1 of this Edition; Table 1 of the 2008 Edition);
--- Modify the dimensional limit deviations of the wet surfaces of guide vanes with Class-A
accuracy (see Table 2 of this Editon; Table 3 of the 2008 Edition);
--- Add the requirements for the hydraulic dimensional tolerances of the wet surfaces of
pump castings of other structural types (see 3.5 of this Edition).
This Standard was proposed by China Machinery Industry Federation.
This Standard shall be under the jurisdiction of National Technical Committee on Pumps of
Standardization Administration of China (SAC/TC 211).
Drafting organizations of this Standard: Shenyang Casting and Forging Industry Co., Ltd.;
Shijiazhuang Kingda Pump Group Co., Ltd.; Shanghai Kaiquan Pump (Group) Co., Ltd.;
Shimge Pump Industry Group Co., Ltd.; Leo Group Pump (Zhejiang) Co., Ltd.; Chongqing
Pump Industry Co., Ltd.; Zhejiang Keer Pump Stock Co., Ltd.; Jiangsu Wuxin Pump Industry
Co., Ltd.; EBARA Great Pumps Co., Ltd.; Hangzhou Alkali Pump Co., Ltd.; Xiamen Koyur
Technology Co., Ltd.; Yiwu Shuanghong Mould Factory; and Shenyang Pump Research
Institute.
Chief drafting staffs of this Standard: Li Wanpeng, Yang Wen, Wang Yanhe, Ling Guirong,
Wang Lin, Bai Xiaobang, Chi Wu, Liu Ming, Qu Jingtian, Li Jinfu, Duan Chunfang, and Kang
Na.
The historical editions replaced by this Standard are as follows:
--- JB/T 6879-1993, JB/T 6879-2008.
Dimensional Tolerances of Wet Surfaces in the Castings of
Centrifugal Pumps
1 Scope
This Standard specifies the dimensional tolerances and technical requirements for the wet
surfaces in the castings of centrifugal pumps.
This Standard applies to all wet surfaces in metal castings of centrifugal pumps except light
metal parts and abrasion-resistant white iron casting.
2 Basic Provisions
The dimensional tolerances of the wet surfaces in the castings of centrifugal pumps are divided
into three accuracy levels: A, B, and C. The dimensional limit deviation values are shown in
Tables 1 ~ 3 according to different wet surfaces.
3 Technical Requirements
3.1 The selection of accuracy levels shall meet the following requirements:
a) Level-C is a general one. For centrifugal pumps with low performance deviation
requirements, Level-C can be used;
b) When Level-C is used, the performance deviation of the centrifugal pump cannot meet
the requirements and needs to be met by changing the dimensional tolerance, then Level-
B can be used;
c) Impellers and guide vanes that are required to be precision cast by investment casting or
ceramic casting can use Level-A.
3.2 For castings that are required to be manufactured according to Level-C, the accuracy level
is not marked in the drawings. For castings that are required to be manufactured according to
Levels-B or -A, the accuracy level shall be indicated in the drawings or technical documents.
3.3 The impeller, guide vane, and volute castings of the centrifugal pump are shown in Figures
1, 2, and 3, respectively. The dimensional limit deviations of the wet surfaces shall comply with
the provisions of Tables 1, 2, and 3, respectively. The blade misalignment of the intermediate
parting is shown in Figure 4, and the maximum allowable misalignment value shall comply
with the provisions of Table 4.