GB 12235-89 Steel Gate Valve and Lift Check Valve with Flange Connections
This GB 12235-89 standard is suitable for the production of medium and low-pressure steel gate valves and lift check valves with flange connections. It regulates the technical conditions, product inspection and acceptance, and also stipulates its quality assurance measures. It is dedicated to providing qualified products for users and protecting their legitimate interests.
Scope
This standard applies to the production of cast steel gate valves and lift check valves with nominal pressure PN1.0～4.0MPa and DN15～DN400 nominal diameter (including 15, 20, 25, 32, 40, 50, 65, 80, 100, 125, 150, 200, 250, 300, 350, 400); Flange dimension for the use of products with nominal pressure PN1.6Mpa and GB/T 9113.1-2000 (I-type flange sealing face), PN2.5～4.0MPa uses GB/T 9694.1-2005 (II-type pressure type Flange seal face).
Material Ingredients
Valve body, bonnet and disc: ZG230-450, ZG1Cr18Ni9Ti, ZG1Cr18Ni12Mo2Ti
Valve seat and seal rings: G20CrMo, G3CrNiMo, G30Cr2MoNi, G40CrNi, 1Cr18Ni9Ti
Stem: 2Cr13, 2Cr13Ni, 0Cr18Ni9Ti, 1Cr17Ni2
Gasket: stainless steel, copper-based alloy
Packing and seals: fluorine rubber and flexible graphite
Inspection and Examination
Sketching of Definition
The definition and sketching of roughcastings and machined for the production of steel gate valves and lift check valves and their components shall comply with the requirements of drawings.
Dimension Calibration
Before assembly, it is necessary to calibrate the dimensions of the components of the steel gate valve according to the dimensions in the drawing. The dimensions of the lift check valve should also be calibrated.
Inspection of Materials
Inspect incoming materials. The chemical composition and mechanical properties of the materials shall meet the requirements of this code. The physical and chemical properties of the components at the users request shall also be inspected and the hygienic certificates shall be provided.
Release of Finished Products
After the completion of the production of steel gate valves and lift check valves, perform a static performance test to think whether the corresponding products meet the requirements of this code.
Product Identification
The product identification of the steel gate valve and lift check valve shall be marked according to the size of the nominal diameter and pressure, the grade of the materials used in production, the manufacturers trademark, the production batch number or the casting number, the nominal pressure symbol and the directions of opening and closing of the valves.
Quality Assurance Measures
Raw Material Control
The manufacturers material purchasing organization should have control measures for the quality of raw materials, and ensure that the purchased products meet the requirements. Iron and steel raw materials must be inspected and accepted by the competent units in accordance with the relevant national standards before being put into production.
Production Technology Control
Valve manufacturers should formulate detailed production process documents, process documents and process cards for steel gate valves and lift check valves, and strictly implement them in production.
Control of Nonconforming Products
Valve manufacturers shall set up a special control room to control non-conforming products and establish product markers, specifications, and catalogues of non-conforming products.
Valve Production Storage
The valves produced shall be inspected pass in accordance with the requirements, and they are not allowed to be transported until they have passed. The valve is to be stored in a dry, clean and well-ventilated place, and strictly prohibited from being exposed to rain and sun, affected by temperature and humidity, otherwise rust and aging of valves will occur.
Conclusion
The production of GB 12235-89 steel gate valves and lift check valves with flange connections shall strictly follow the corresponding standards and pass the relevant tests. The purpose of this article is to explain and demonstrate the major features and characteristics of this particular GB standard, offering an overview of the major steps of the production process and providing quality assurance measures. In order to provide customers with qualified and high-quality products, valve manufacturers should strictly follow the standard and provide products that meet the requirements of the standard.
