JB/T 7927-1999 This standard is a revision of JB/T 7927-95 "Appearance Quality Requirements for Valve Steel Castings" and supplements and modifies the interpretation of defect terms in the original standard. This standard is equivalent to the American Manufacturers Association standard MSS-SP55-1996 "Quality Standards for Steel Castings of Valves, Flanges, Fittings and Other Pipeline Accessories, Visual Inspection Method for Surface Defect Assessment". This standard specifies the types and characteristics of surface defects of valves, flanges, fittings and other pressure castings. This standard is applicable to the visual inspection and acceptance of the surface quality of valves, flanges, fittings and other pressure castings. This standard was first issued in 1989 as GB 12231-89 and was adjusted to JB/T 7927-95 on April 14, 1996. JB/T 7927-1999 Appearance quality requirements for valve steel castings JB/T7927-1999 Standard download decompression password: www.bzxz.net

ICS23.060
Standard of the Machinery Industry of the People's Republic of China
JB/T7927-1999
Valve cast steel
Appearance quality requirements
Valve cast steel visual qualityrequirements1999-07-12 Issued
National Bureau of Machinery Industry
2000-01-01 Implementation
JB/T79271999
This standard is a revision of JB/T7927-95 "Appearance quality requirements for valve 1 steel castings". During the revision, editorial changes were made to the original standard, and the explanations of the defect terms in the original standard were supplemented and modified. This standard is equivalent to the American Manufacturers Association standard MSS-SP551996 "Quality Standard for Steel Castings of Valves, Flanges, Pipe Fittings and Other Pipeline Accessories, Visual Inspection Method for Surface Defect Assessment". This standard replaces JB/T7927--95 from the date of implementation. This standard is proposed and managed by the National Valve Standardization Technical Committee. The drafting units of this standard: Kaifeng High-Pressure Valve Factory, Hefei General Machinery Research Institute. The main drafters of this standard: Hu Meihua, Chen Yujuan, Jiao Lunling, Jia Jinwen, Zheng Qinglun 1 Scope
Machinery Industry Standards of the People's Republic of China
Valve Cast Steel
Appearance Quality Requirements
Valvecaststeelvisualqualityrequirements This standard specifies the types and characteristics of surface defects of valves, flanges, pipe fittings and other pressure castings. JB/T7927-1999
Replaces JB/T7927-95
This standard applies to the visual inspection and acceptance of the surface quality of valves, flanges, pipe fittings and other pressure castings. 2 Surface Quality Assessment
Steel castings should be inspected visually after cleaning and trimming and before painting, and various defects on their surfaces should be compared and assessed based on the photos specified in this standard (see Chapter 4). 3 Explanation of Rating Photos
3.1 This standard collects 12 types of surface defects (see 4.1 to 4.12), and each defect type includes 5 examples represented by A, B, C, D, and E. The 2 examples shown in A and B are to show that defects of this degree are acceptable (qualified), and the 3 examples of C, D, and E are unacceptable (unqualified) defects. Considering that using the same standard to judge the surface of castings with too wide a range of sizes and thicknesses will cause problems, the 60 photos provided in this standard are examples of the actual size of any 4"×5" (100mm×125mm) area on the surface of the specified casting. 3.2 The explanation of the terms of all defect types [type a) to type c)] in the rating photos only applies to surface defects. The types and characteristics of various surface defects are as follows:
a) Cracks: Linear cracks appearing on the surface of steel castings due to internal and external stresses. Usually, obviously visible surface cracks are unqualified.
b) Shrinkage holes: Due to metal shrinkage, holes with extremely irregular shapes, rough hole walls and dendrites exist at the pouring and riser cutting of steel castings.
c) Sand (slag) eyes: Due to sand particles rolling into molten metal, holes with sand particles (slag) are formed on the surface of steel castings. d) Porosity: Due to the presence of gas in the molten metal, holes of varying sizes with relatively smooth hole walls, such as pear-shaped, round, oval or needle-shaped, are formed on the surface of steel castings.
e) Ridge-like protrusions (meaty): Metal protrusions on the surface of steel castings that are thorny (ridge-like). Burrs with extremely irregular shapes and distributed in a network or vein-like manner are called veining.
f) Rat tail: A shallow (less than 5mm) sharp-angled western mark formed on the surface of the steel casting due to defects or deformation on the sand mold surface.
g) Cold shut and wrinkle: A rounded, penetrating or non-penetrating gap formed on the surface of the steel casting due to incomplete fusion of the metal. Generally, a deep mesh groove on the surface is called a wrinkle. h) Cut scar: A scar left by improper trimming during the cleaning, cutting, pouring and riser process of the steel casting. Approved by the State Bureau of Machinery Industry on July 12, 1999, and implemented on January 1, 2000
JB/T7927—1999
) Scarring: There are metal protrusions in the form of scar flakes on the surface of the steel casting. Its surface is rough, with sharp edges, and a small part of the metal is connected to the main body of the steel casting. There is a sand layer between the scar flake protrusion and the casting. j) Support scar: scar left on the surface of steel casting due to failure of core support or internal cooling iron to melt completely: k) Weld scar: scar left on the welded part of steel casting due to poor post-weld finishing. 1) Rough surface: The surface of steel casting is not smooth and uneven. 4 Rating photos
4.1 Type a): Crack
JB/T7927-1999
JB/T7927-1999
4.2 Type b): Shrinkage
JB/T7927—1999Www.bzxZ.net
JB/T7927—1999
JB/T7927—1999
4.3 Type c): Sand (slag) eyes
JB/T7927-1999
JB/T7927—1999
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