Specific requirements for radiographic testing of valve compression cast steel valve cast steel appearance quality requirements
The casting defects on the film are divided into five categories: air hole, sand and slag inclusion, shrinkage hole and porosity, inner chiller unfused and crack. The pores of the defects in the repair welding area on the negative can be regarded as the evaluation of the casting defects, while the slag in the repair welding area is not dissolved and not welded through can be regarded as the slag inclusion of the casting defects. The defect size is measured according to the size of the defect image on the film. Yes. For the shrinkage cavity, only the size of the obvious part of each defect is measured, not the size of the surrounding fuzzy shadow. When two or more defects partially overlap on the film, their dimensions should be measured separately.
Connection: Specific requirements for radiographic testing of valve compression steel castings (II)
5. Defect classification and evaluation method of radiographic film
5.1 Defect classification and size measurement
5.1.1 Casting defects on the film can be divided into five categories: air hole, sand and slag inclusion, shrinkage hole and porosity, inner chiller unfused and crack. The pores of the defects in the repair welding area on the negative can be regarded as the evaluation of the casting defects, while the slag in the repair welding area is not dissolved and not welded through can be regarded as the slag inclusion of the casting defects.
5.1.2 The defect size is measured according to the size of the defect image on the film. Yes. For the shrinkage cavity, only the size of the obvious part of each defect is measured, not the size of the surrounding fuzzy shadow. When two or more defects partially overlap on the film, their dimensions should be measured separately.
5.1.3 When the defect is connected to the evaluation roll (field of view) boundary, it shall be included in the calculation points within the evaluation area.
5.2 Defect grade of air hole, sand and slag
5.2.1 Select the area with a large number of defect points on the negative film as the evaluation area. The size of the assessment area and the relatively large allowable number of defects are specified in Table 6 and 7.
Table 6 The size of the assessment area and the larger allowable points of pores
Table 7. Size of assessment area and larger allowable points of sand and slag inclusion
5.2.2 The number of points for a single defect shall be specified in Table 8 and according to the size of the defect. However, defects smaller than those specified in Table 9 May not be counted.
Table 8 Number of points for individual defects
Table 9 does not count the number of defects compared to the larger allowable size
5.2.3 Points of two or more defects shall be the sum of points of each defect within the assessment area. It can be evaluated according to Table 6 and Table 7 respectively, but the size of the relatively large pores, sand clamps and cleaning clamps allowed in level 1 shall not exceed that specified in Table io and Table 11 respectively.
Table 10 Relatively large pore sizes allowed for primary defects
Table 11 Comparative large sand clamping and cleaning sizes allowed for primary defects
5.3 Defect grade of shrinkage cavity
5.3.1. Select a relatively large part of the length or area of the defect on the negative for evaluation. The size of the assessment area and the larger allowable size of the defect are specified in Table 12 or 13.
Table 12 Large permissible length of satin for strip shrinkage hole defects
Table 13 The relatively large allowable area of dendritic shrinkage cavity defects
5.3.2 Shrinkage cavity defects can be divided into strip shrinkage cavity, dendritic shrinkage cavity and large area shrinkage cavity according to their shapes.
5.3.3 Calculation of defect length of strip shrinkage hole: a strip shrinkage hole takes the relatively large length of shrinkage hole as the defect length; Two or more strip shrinkage holes is the sum of the length of each shrinkage hole as the defect length. When the shrinkage hole is on the boundary of the assessment area, the part outside the defect line should also be included.
5.3.4 Calculation of the defect area of dendritic shrinkage cavity: a dendritic shrinkage cavity is the product of the larger length of the defect and the larger width of the orthogonal product of the defect area of the shrinkage cavity; Two or more dendritic shrinkage cavities are the sum of the areas of each shrinkage cavity as the defect area. When the shrinkage hole is on the boundary of the assessment area, the part outside the defect line should also be included.
5.3.5 When there are both dendritic and stripe-shaped shrinkage cavities in the evaluation area, the stripe-shaped shrinkage cavity shall be regarded as the branch shrinkage cavity for evaluation. The length of the stripe-shaped shrinkage cavity shall be the length of the stripe-shaped shrinkage cavity, and the width shall be one third of the length.
5.3.6. The large-area shrinkage defect is calculated by the product of the relatively large length of the defect multiplied by the relatively large width orthogonal to it.
5.3.7 The grade of i shrinkage cavity defects shall be assessed according to the length or area of defects in the evaluation area. However, shrinkage cavities smaller than those specified in Table 14 May not be counted as defects.
5.3.8 Strip shrinkage cavity shall be evaluated according to iz according to the sum of defect length in assessment G; The dendritic shrinkage cavity was evaluated according to Table 13 according to the sum of the defect area in the evaluation area. The large area shrinkage is evaluated according to the sum of the defect area in the evaluation area according to the values in brackets in Table 13.
Table 14 The larger size of shrinkage cavity defects without evaluation
5.3.9 Crack (hot crack and cold crack), inner chiller not fused and mud core support not fused on film i shall be classified as grade 6.
5.4 Comprehensive rating of defects
5.4.1 In the assessment area, if there are two or more types of defects at the same time, the classification shall be carried out respectively according to the types of defects, and then the comprehensive rating shall be carried out according to the method given in 5.42~5.4.4.
5.4.2 In the assessment area, if there are defects of homogeneous or two types of soil and the grade is not simple, the lower grade shall be taken as the comprehensive rating.
5.4.3 In the assessment area, if there are two or more types of defects with the same grade, the comprehensive rating shall be reduced by one level. In the case of two or more types of Class i defects, ‘the defect shall be classified as Class 2 when the number, length or area of the defect exceeds 1/2 of the allowable value. However, a defect classified as level 2 according to Table 10 or Table 11, or a defect classified as level 2 according to Table 9 and Table 14, which is beyond the scope of application of Level i without the comparative size of the defect, will be classified as level 2 even if it is mixed with some other level 2 defect.
5.4.4 If the reviewer thinks that the defect has safety hazards, it can be judged as unqualified.
Steel castings of valves shall be inspected for a second after being dressed and trimmed, and shall be evaluated for various defects on the surface according to the photos specified in this standard (see Chapter 4). This standard collected 12 surface defect age types (see 4.1–4.12, each defect type includes 5 cases represented by A, B, C, D and E. All defect types [type a} light c}} terms in the rating photos are explained only for surface defects. The types and characteristics of various surface defects are described as follows:
This standard specifies the types and characteristics of surface defects in valves, flanges, pipe fittings and other compression steel castings.
This standard applies to the visual inspection and acceptance of the surface quality of valves, flanges, pipe fittings and other compression steel castings.
2. Surface quality assessment
The steel castings should be inspected for a second after being repaired and trimmed, and the defects on the surface of the castings should be evaluated according to the photos specified in this standard (see Chapter 4).
3. Rating the caption of the photo
3.1 This standard collects 12 surface defect age types (see 4.1–4.12), each defect type includes 5 cases represented by A, B, C, D and E, two cases shown by A and B are acceptable (qualified), and three cases of C, D and E are unacceptable (unqualified) defects. In consideration of the problems caused by waxes using the same standard to determine the size of overwidth of the casting surface, the 60 photographs provided in this standard are examples of actual size drawings of any 4 X 100 mm X 125 mm area of the specified casting surface.
3. 2 All defect types in the rating photos [Type a} light c}} terms are explained to apply only to surface defects. The types and characteristics of each surface defect are described as follows:
a} crack: linear cracking on the surface of steel castings due to the action of internal and external stresses. Usually visible surface cracks are not qualified.
b) Shrinkage cavity: Due to metal}}L-1}}, in the pouring and riser cutting of steel castings, the shape is extremely irregular, the wall is rough and there are dendri-like crystal holes.
C) Sand (slag) holes: holes with sand (slag) formed on the surface of the steel cast due to the involvement of sand into the molten metal.
d) Pores: due to the mixture of gas in the molten metal, and the formation of different sizes on the surface of the skim l “, the hole wall is smooth and pear shaped, round, oval or needle shaped holes.
e (Ridged projection): A spike (ridge) shaped metal projection on the surface of a steel cast. The shape of the extremely irregular, reticular or vein-like distribution of burrs called veins.
f) Rat tail: shallow (less than 5~) indentations with acute angles are formed on the surface of the skimmer due to defects or deformation of the sand surface.
g) Cold separation and crease: penetrative or impenetrable crevices formed on the surface of steel castings in the shape of rounded corners due to incomplete integration of the dance type. In the epidermis generally with a deeper network of grooves called creases.
h) Cutting scar: the scar left by improper dressing in the process of cleaning, cutting, pouring and rising steel castings.
i) Scar: metal protrusions formed on the surface of steel castings are scar-like. The surface is rough, the edge is sharp, there is a small sound hope metal and the handcuffed steel body is connected, and there is a sand layer between the scar and the casting.
j} Brace scar: A scar left on the surface of a steel cast because the core brace or inner chiller failed to melt completely.
k) Welding scar: the scar left on the welding repair of steel casting due to poor repair after welding.
l) Rough surface: the surface of the steel cast is not smooth and uneven.
4 Rating Photos
4. 1 Type a): Crack
Post time: Nov-24-2022