BS ISO 4987:2020 pdf download – Steel castings — Liquid penetrant testing
5 Testing
5.1 Operating mode Testing shall be carried out as specified in ISO 3452-1.
5.2 Qualification of the operators
Testing shall be performed by personnel qualified in accordance with ISO 9712 or equivalent recognised standards. The qualification level of the personnel shall be agreed between the manufacturer and purchaser by the time of the acceptance of the order.
5.3 Surface preparation The surface to be tested shall be clean and free from oil, grease, moulding and coating residues, or any other contaminant which could interfere with the correct implementation and interpretation of the penetrant testing results. For small indications, it may be necessary to improve the surface condition. Annex A provides guidance on recommended surface finish for testing based on indication allowed. Surface treatment or cleaning techniques which may seal or close discontinuities are not allowed. 5.4 Conditions of testing The testing shall be carried out unaided or at a maximum magnification of 3× under viewing conditions in accordance with ISO 3059.
6 Acceptance criteria
6.1 Definition of liquid penetrant indications
6.1.1 General Indications revealed by the liquid penetrant testing can have different shapes and sizes. The distinction between the indications is made depending on the ratio of the length L of the indication to its width W, in the manner described in 6.1.2 and 6.1.3.
6.1.2 Non-linear indications (SP) Indications are considered to be non-linear when the length L is smaller than three times the width W. Indications are considered to be aligned when the distance between non-linear indications is less than 2 mm and at least three indications are aligned. An alignment of indications is considered to be a unique non-linear indication and its length is equal to the overall length L of the alignment specified in Table 1. Non-linear indications that are not aligned are considered to be isolated. NOTE The symbol for non-linear indications is SP (S for surface and P for liquid penetrant).
6.2 Severity levels
6.2.1 General
The severity levels are a reference scale, each level depends on the types of indications.
6.2.2 Non-linear indications
For the non-linear indications, the severity levels (see Table 1) are defined by:
a) the length (largest dimension) L 1 of the smallest indication to be considered, and
b) the maximum length L 2 of the indications.
6.2.3 Linear indications General
The severity levels for linear indications (see Table 2) are defined by:
a) the length (largest dimension) L 1 of the smallest indication to be considered,
b) the maximum length L 2 of the linear individual (I) indications, and
c) the total (T) of the lengths of the linear indications exceeding the length L 1 in a frame measuring
105 mm × 148 mm. Section thickness type
Three section thickness types are specified (see Table 2):
a) t ≤ 16 mm;
b) 16 mm < t ≤ 50 mm;
c) t > 50 mm;
where t is the section thickness.
6.2.4 Selection of the severity level The severity levels shall be selected from Tables 1 and/or 2 as seen in, if necessary, the reference figures given in Annexes B and C. The reference figures are drawn to a scale of 1:1 and are given as examples. The largest non-relevant indication is shown in a 26 mm × 37 mm frame corresponding to the ISO format A10. Table 1 and Annex B correspond to non-linear (SP) indications (isolated). Table 2 and Annex C correspond to linear (LP) indications.
NOTE Note that several equivalent severity levels defined in Table 2 are represented by the same reference figure. In certain cases, the equivalence of the figure is only approximate because of slight differences in the parameters in Table 2. The severity levels cannot be considered in the same progression from Table 1 to Table 2. They should not be considered equivalent as regards severity. The severity criteria and the severity levels can differ from one part of a casting to another.BS ISO 4987 pdf download.