EN 1971-2-2011 pdf download.Copper and copper alloys – Eddy current test for measuring defects on seamless round copper and copper alloy tubes – Part 2: Test with an internal probe on the inner surface.
This EN 1971-2 specifies a procedure foi- the eddy current test with an internal probe for measuring defects on the inner surface of seamless round copper and copper alloy tubes.
This European Standard applies particularly for finned tubes with high fins according to EN 12452.
NOTE The eddy current test method(s) required, together with the site range and acceptance level, are defined in the relevant product standard.
The choice of the method for eddy current test:
— with an encircling test coil on the outer surface according EN 197 1-1
— with an internal probe on the inner surface according EN 1971-2
is at the discretion of the manufacturer if there are no other agreements between the purchaser and the supplier. Especially for finned tubes according to EN 12452 with high fins, It is recommended to use eddy current test with Internal probe as described in this standard.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 473. Nan-destructive testing — Qualification and certification of NOT personnel— General principles EN ISO 12718, Non-destructive testing — Eddy current testing — Vocabulary (ISO 12718:2008)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN ISO 12718 apply.
4 General requirements
4.1 Personnel qualification
The eddy current test shall be made by operators trained in this technique and it shall be done under the responsibility of qualified staff.
When agreed upon between the purchaser and the supplier, qualification of the personnel shall be certified according to EN 473.
Test speed over the length of the tube shall be as constant as possible.
The distance between the probe and the inner surface of the tube shall be kept as small as possible so that the sensitivity of the test is sufficient.
NOTE For internal probes, the usual frequencies are in the range 1 kHz to 125 kHz.
5 Reference standard tube
Unless otherwise specified in the relevant product standard, a reference standard tube is made of a defect- free tube of the same dimensions and specified properties as the tube to be tested.
During the reference test, the influence of dynamic conditions shall be taken into account.
NOTE The producer can ensure that this requirement is met by the appropnate option subject to the type of the Installation, such as:
a) for control devices not in-line with p’oduction, the reference tube should be long enough to ensure the same dynamic conditions for the reference test as for normal line operating speed;
or
b) the control devices should include a dynamic effect compensating unit to take into account the speed differences between the reference tube throughput speed and the normal line operating speed.
Either the reference standard tube shall have three holes located on three generating lines at 120°. or only one hole. If a reference standard tube with three holes is used, the holes shall be spaced from each other and from each end, sufficiently to obtain separate signals from each hole without interference from the tube ends. If a reference standard tube with only one hole is used, then this tube shall be used three times being turned by 120°.
The maximum drill diameter for the various dimension ranges is defined in the relevant product standards.
Other reference standard tube types may be considered if they are demonstrated as more relevant for certain
products; they shall be defined in the relevant product standards.
6 Acceptance criteria
6.1 Detection of local discontinuities by internal probes systems
Local discontinuities of the tubes, including beginning and end of long regular discontiriuities and variations of long discontinuities. are detected as defects with internal probes systems.
The sorting limit shall be the smallest amplitude of the three signals produced by the hole or holes in the reference standard tube.
6.2 Detection of non-local discontinuities by internal probes systems with lower detection levels
Non-local discontinuities of the tube could be identified as defects by one of the methods defined for this purpose, according to the requirements of the relevant product standards.
Some discontinuities of the tube, which individually are not considered as defective, might cause signals lower than the detection threshold of the normal sorting limit for local defects but higher than a second selected lower detection threshold S1. The signals for the lower and normal detection thresholds are related by a ratio k2, which shall be determined by the manufacturer of the tube, as follows:EN 1971-2-2011 pdf download.