1 Scope
This document specifies the type and designation, dimensions, technical requirements, test methods, inspection rules, marking, symbols, ordering information, packaging and storage of wound gaskets for pipe flanges (hereinafter referred to as "gaskets") with Class designation.
This document applies to wound gaskets for pipe flanges with nominal pressures from Class 150 to Class 1500 and nominal sizes from DN 15 to DN 600 (NPS4 to NPS 24) as specified in GB/T 9124.2.
2 Normative references
The contents of the following documents constitute essential provisions of this document by means of normative references in the text. Where the references are dated, only the version corresponding to the date applies to this document; where the references are not dated, the latest version (including all amendment sheets) applies to this document.
GB/T 2054 Nickel and Nickel Alloy Plate
GB/T 3003 Refractory Fiber and Products
GB/T 3274 Carbon Structural Steel and Low Alloy Structural Steel Hot Plate and Strip
GB/T3280 Cold Rolled Stainless Steel Plate and Strip
GB/T5019.4 Mica based insulating materials Part 4; Mica paper
GB/T 12385-2008 Test Method for Performance of Gasket Strip Seals for Pipe Flanges
GB/T 12,622-2008 Test Method for Compressibility and Resilience of Gaskets for Pipe Flanges
GB/T 27793 asbestos free fiber gasket material
JB/T 6618 Technical Conditions of PTFE Tape for Metal Wound Gasket
JB/T 7758.2 Technical Conditions for Flexible Stone Slab
3 Terminology and definitions
There are no terms and definitions that need to be defined in this document.
4 Type and designation
4.1 Type
4.1.1 The type of wound gaskets is shown in Figures 1 - 4.
4.2 Designations
The winding gasket type designations are as specified in Table 1.
5 Dimensions
5.1 Dimensions of basic type wound gaskets for flanges with tongue and groove faces
The dimensions of the basic (Type A) wound gasket for tongue and groove flanges shall be in accordance with Figure 1 and Table 4.
5.2 Dimensions of winding gaskets with inner ring for flanges with concave and convex faces
The dimensions of the winding gasket with inner ring (type B) for concave and convex flanges shall be in accordance with the provisions of Fig. P.C. and Table 5.
Table 5: Dimensions of the winding gaskets with inner ring (Type B) for flanges with concave and convex faces
5.3 Dimensions of wound gaskets with locating rings for flat and raised face flanges
The dimensions of wound gaskets with locating rings (Type D) for flat and raised face flanges shall be in accordance with Figure 3 and Table 6.
5.4 Dimensions of wound gaskets with inner and locating rings for flat and raised face flanges
The dimensions of the wound gaskets with inner ring and locating ring (type D) for flat and protruding flanges shall be in accordance with Figure 4 and Table 7.
6 Technical requirements
6.1 Materials
6.1.1 Metal strip
6.1.1.1 You shall use cold rolled steel strip with a thickness of 0.190 mm ± 0.040 mm for the metal strip. Other materials than those in Table 2 are permitted according to the agreement between supply and demand. The surface of the strip shall be free from defects affecting its performance.
6.1.1.2 The chemical composition and mechanical properties of the stainless steel strip material shall conform to the provisions of GB/T 3280, and other materials shall conform to the provisions of the relevant standards.
6.1.2 Filled strips
6.1.2.1 ﹑ filler tape material code and the recommended use of temperature, see Table 3. according to the consultation between supply and demand, can choose other filler materials, and meet the provisions of the relevant standards. The thickness and density of the filling material shall be determined by the manufacturer, but shall meet the performance requirements of 6.5.
6.1.2.2 The technical requirements of the flexible graphite tape for gaskets shall be in accordance with JB/T 7758.2.
6.1.2.3 The technical requirements for PTFE tapes for gaskets shall be in accordance with JB/T 6618.
6.1.2.4 Non-asbestos fibre tape for gaskets shall conform to the provisions of GB/T 27793.
6.1.2.5 Ceramic-based composites for gaskets shall comply with GB/T 3003 K6.1.2.6 Mica-based materials for gaskets shall comply with GB/T 5019.4
6.1.2.7 High temperature resistant laminated silicate composites for gaskets shall comply with the relevant inter-standard regulations.
6.1.3 Inner rings and locating rings
6.1.3.1 Unless otherwise agreed between supply and demand, the corrosion and temperature resistance of the inner ring material shall be equal to or better than that of the metal strip.
6.1.3.2 Gaskets for flat (FF) or raised face (RF) flanges with PTFE filler tape shall be provided with an inner and locating ring.
6.1.3.3 Gaskets for flat (FF) or raised face (RF) flanges with a nominal pressure of Class 300 and above shall be provided with an inner ring and a locating ring.
6.1.3.4 The material of the inner ring and locating ring shall comply with GB/T 3274, GB/T 3280, GB/T 2054 or related standards.
6.2 Process requirements
6.2.1 The gasket shall be made of prefabricated metal strip and non-metallic filler strip wound alternately, the metal strip and the filler strip shall be tightly fitted, with a clear and even texture, without folds and gaps. The sides of the filler tape should be uniformly higher than the metal tape by approx. 0.2 mm and the metal tape should not be visible.
6.2.2 At least three layers of unfilled prefabricated metal tape shall be used for the initial winding. The two initial windings should start with a minimum of three spot welds along the circumference at a maximum spacing of 75 mm. The final winding should also have a minimum of three layers of unfilled prefabricated metal tape. A minimum of three spot welds along the circumference and a final spot weld is the terminal weld.
6.2.3 The distance between the terminal weld and the previous weld shall not be greater than 35 mm. The terminal weld of the gasket with the locating ring shall be followed by a winding of not more than 4 turns of prefabricated metal tape to adjust the gap between the locating ring and the sealing element and to ensure that the locating ring does not fall off.
6.2.4 The inner ring and locating ring may be machined from the whole plate or from the splice, but the quality of the interface shall be guaranteed. The ring surface should be flat and the tolerance of its flatness should be less than 1%; the inner side of the positioning ring should have a groove of about 1.5 mm in depth to assemble the sealing element, the groove or chamfer should be concentric with the inner and outer circle and symmetrical with the two end surfaces.
6.2.5 The gasket with inner ring can be made by winding directly on the outer circle of the inner ring, or by using special equipment to fix the inner ring and the sealing element tightly.
6.2.6 No mechanical processing or pre-pressing is permitted on the surface of the sealing element after it has been wound and formed.
7 Inspection methods
7.1 Appearance quality
The appearance of the gasket is visually inspected.
7.2 Dimensional measurements
7.2.1 The thickness of the gasket (T, T,) is measured with an accuracy of not less than 0.01 mm using the arithmetic mean of three points of equal arc.
7.2.2 Gasket diameters (Dy, Ds, Ds, D,) are measured with a gauge with an accuracy of not less than 0.10 mm and the arithmetic mean of the two mutually perpendicular or more than two equal-arc measurements; gaskets with an accuracy of not less than 1.0 mm are used for gasket diameters larger than 1 000 mm.
7.2.3 - Gaskets with basic and inner rings should avoid welding joints when measuring the diameter of sealing elements.
Note: Due to the different assembly processes of the positioning ring, the outermost layer of the sealing element is allowed to have no more than 4 turns of prefabricated metal tape for adjusting the positioning ring to the sealing element.
The size of the gap formed by the number of turns and the tightness of the assembly is uncertain, so that the positioning ring does not fall off (see 6.2.3) and meets the performance requirements (see 6.5). ).
7.3 Performance test
7.3.1 The compression performance of the gasket is tested according to Table 10 and the test equipment according to GB/T 12622-2008 test method B. The thickness after compression is calculated according to formula (1), accurate to 0.01 mm:
8 Test rules
8.1 Inspection classification
The gasket inspection is divided into factory inspection and type inspection.
8.2 Factory inspection
8.2.1 The gasket shall be delivered only after it has been inspected by the manufacturer's quality inspection department in accordance with this document and after a quality certificate has been issued.
8.2.2 The factory inspection items for gaskets are dimensional deviation (6.3>, appearance quality (6.4).
8.2.3 During the factory inspection, the appearance quality shall be fully inspected in accordance with 6.4. For gaskets of the same material combination and of the same structural type, 5 pieces of gaskets shall be taken in a batch of 100 pieces, and each batch shall be subject to dimensional inspection in accordance with 7.2; 3 pieces of gaskets shall be taken in a batch of 100 pieces, and the full inspection shall be required if the sample quantity is not sufficient. If any one piece does not conform to the provisions of this document, the gasket shall be retested by taking the amount of Gaggedon, and if one piece does not conform to the provisions of this document, the batch shall be fully inspected.
8.3 Type test
8.3.1 The gasket type test items are appearance quality (6.L dimensional deviation (6.3), performance requirements (6.5).
8.3.2 For the type test, a batch of gaskets of the same material combination shall be tested by taking 3 pieces of each of the specimens specified in Table 10 and Table 11, or by making a sufficient number of specimens according to the same process if there are no specimens. If 1 piece of any item does not conform to the provisions of this document, double the number of shims shall be taken for re-testing of that item. If 1 piece still does not conform to the provisions of this document, the batch shall be judged to be unqualified or the type test shall fail.
8.3.3 The type test shall be carried out in one of the following cases
(a) new products or transfer production of the trial production, finalization and identification.
b) After formal production, the gasket structure, material and process have changed significantly, which may affect the performance of the product.
c) 1 year of normal production.
d) Production has been suspended for more than 3 months to resume production.
e) Type test requested by the national quality supervision body or by the user.
9 Marking, marking. Ordering information, packaging and storage
9.1 The gasket shall be marked with the following elements.
Appendix A (informative) Order information for the user
Bibliography
1 Scope
2 Normative references
3 Terminology and definitions
4 Type and designation
5 Dimensions
6 Technical requirements
7 Inspection methods
8 Test rules
9 Marking, marking. Ordering information, packaging and storage
Appendix A (informative) Order information for the user
Bibliography
