CZ35562U1 - Test specimen with welded coupons - Google Patents

Description

Test specimen with welded coupons

Field of technology

The technical solution concerns a test specimen with welded coupons, used for operator training and qualification of the entire measuring system of non-destructive inspections. Thanks to the use of test specimens, the reliability of the results from the performed non-destructive testing in operation increases significantly, and thus the increase in operational safety is increased. These high requirements for the accuracy and reliability of non-destructive testing results can be found mainly in the energy and chemical industries. Non-destructive testing technology is mainly used to look for manufacturing and / or operational defects. Various non-destructive testing techniques such as radiographic method, ultrasonic method, penetration method, magnetic pouring method, acoustic emission method and the like are used for this purpose. The functionality and sensitivity of these non-destructive methods must first be verified on so-called test specimens. These bodies have a variety of shapes and materials. Both simple sheets and profiles as well as very complicated machine parts or welded structural units made of various materials, including composites, can be used as test specimens. The test pieces are manufactured in such a way that, if possible, they are a true copy of the tested part in operation, or as close to it as possible.

State of the art

A well-set non-destructive measuring system determines the presence, position or dimensions of the defect (depth, length) in the test specimen in accordance with the inspection procedure. An incorrectly set non-destructive measuring system such as an uncalibrated instrument, untrained operator or an error in the measurement procedure will generate results that do not correspond to the tested defect or completely overlook it. For the needs of qualification of the given technology of non-destructive testing and training of operators, test bodies with artificial defects are used. These man-made defects must have known dimensions and locations in the test piece.

Test specimens contain one or more man-made defects. The most common are test specimens containing replacement defects such as a flat-bottomed bore or an EDM groove simulating a real defect. Replacement defects are produced by routine machining operations. Their advantage lies in the precisely known dimensions and location. Replacement defects are an idealized and simplified simulation of an actual operational defect and usually have a direct determination of which area of non-destructive measurement they are suitable for.

Realistic defects, compared to replacement defects, faithfully imitate operational defects. They are created by similar or identical processes that are commonly created in operation. A partial disadvantage of realistic defects is the determination of their exact geometry and dimensions. However, unlike operational defects, they are intentionally created in a pre-selected area and, thanks to the controlled environment in the laboratory, they are created in an order of magnitude shorter time than in operation. From the point of view of non-destructive measurement, these realistic defects behave identical to the defects from operation when observed by various non-destructive methods. The production of realistic defects is more technologically demanding than the production of spare parts and it is often, due to physical or technological limitations, extremely technically and financially demanding to produce more realistic defects in one body. Due to physical and mechanical processes, individual defects tend to merge into one to a greater extent. The pitfalls of realistic defects are often difficult to verify dimensions. In particular, their depth can only be verified by indirect measurement methods. For replacement defects, the dimensions are given by the machine tool settings. For bodies with realistic crack defects, the depth of the defect is determined by a combination of different non-destructive (NDT) methods. However, the depth determined in this way contains uncertainty in the accuracy of the measurement.

-1 CZ 35562 UI

Therefore, especially from the point of view of the qualification of non-destructive measuring systems, it is advantageous to have a test body with a realistic defect and at the same time with a precisely defined geometry and dimensions of the defect in the test body. Ideally, one body should contain more than one such defect.

The object of the inventors was therefore to combine the said requirements into a solution which would eliminate the said drawbacks and be applicable in practice.

The essence of the technical solution

These shortcomings are partially eliminated by the test body with welded-on coupons, according to this technical solution, the essence of which is that the defects are manufactured separately in the parts referred to as coupons. Defective coupons are incorporated into the base material without defects. Their connection creates a test body containing defects of known geometry and dimensions. The connection of the coupons and the basic material of the body ensures a welded joint, which is unrecognizable for the given non-destructive method.

The proposed technical solution of independent development of defects in coupons and their subsequent integration into the whole test specimen significantly reduces the above-mentioned physical or technological limitations of the production of realistic defects and enables the production of a test specimen with a larger number of realistic defects. The big advantage is the possibility of measuring defects in coupons by methods (including destructive methods), which are no longer feasible after welding into the whole. The usability of the body for visual, capillary, magnetic, ultrasound and X-ray techniques of non-destructive testing and their qualification is also preserved.

The test piece with welded coupons can be divided into two parts. Basic material of the test specimen and coupon (s). The exact connection of the coupon and the base material of the defect-free body is crucial for the applicability of the resulting test body. For this connection, it is suitable to use welding procedures creating small welds with the smallest possible heat affected area. Examples are electron, laser or friction welding.

The basic material of the body is a part of the test body, which is verified by non-destructive testing to be free of defects and exactly corresponds to the part of the simulated part from operation and has a defined space for the location of the coupon. The space for the coupon is located within the whole body so that it can faithfully simulate the most common place of occurrence of the inserted defect. Any construction profile, part, component or weldment serves as the basic material. The coupon also corresponds to all the parameters of the tested part from operation, with the difference that it has the dimensions adjusted to fit in the space defined for the coupon in the basic part of the body, and contains the manufactured defect. The coupon usually contains one defect, but may contain more than one requirement.

The dimensional parameters of the coupon make it easier to create especially realistic defects such as a crack. In general, it may contain a defect of any nature. The defect coupon is thoroughly measured before welding in order to maximally document the geometry and dimensions of the defect.

After welding the coupon into the base material of the body, this joint should be verified that it is not detectable for a given non-destructive method. For example, a weld can be machined to unify and align surfaces. This increases the usability of the body, for example for capillary tests, and reduces the possibility of false indications from the weld.

Clarification of drawings

The technical solution will be explained with the help of the drawing, where Fig. 1 represents the basic material - a perfect part of the body with a prepared cylindrical hole for the coupon and Fig. 2 represents the coupon with a defect. Fig. 3 shows the pressing of the coupon into the base material of the body, Fig. 4

Fig. 5 is a marked area for forming a welded joint, and Fig. 5 is a drawing of the assembly of the resulting body. Giant. 6 shows the final body with a welded coupon. Giant. 7 shows an example of the use of the described technological procedure on a geometrically simpler example with parallel welding.

Examples of technical solutions

A prototype was made to verify the manufacturability and usability of the body with the welded coupon 2. The weldment is made of stainless steel sheet with dimensions of 200 x 200 mm and a sheet thickness of 20 mm. The base material of the body 1 contains a cylindrical hole of high precision.

The coupon 2 is made of the same material in the shape of a cylinder fitting into a hole in the base material.

The coupon 2 is made with a temporary bearing so that it can be pressed into the hole.

In this case, the coupon 2 has a greater height than the thickness of the plate in order to be able to contain the insertion part. This bevel-shaped insertion part is removed by machining after pressing.

In coupon 2, a notch was artificially made before pressing. Depending on the needs, coupon 2 can be exposed to various physical and chemical processes in order to create various realistic and compensatory defects.

Coupon 2 was pressed into the base material of the body and the pressing allowance was machined. Subsequently, an electron beam weld was performed for a permanent connection.

In FIG. 4 schematically shows the division of the test body 1 into a part of the base material 3 (hatched) and a coupon (dotted). Giant. 5, 6 and 7 show a specific implementation of the prototype.

Examples of other variants of technical solution

The defect coupon 2 does not have to be completely surrounded by the base material of the body 1 on all sides. Thus, variants of welded coupons 2 from the side to the base material of the body 1 and the like are also possible. A drawing of a body made of simple steel strips of a weldment is shown in Fig. 7

Non-destructive testing on the body

Non-destructive testing can be performed on the body 1 with welded coupons 2 to the same extent and under the same conditions as on the actual body, taking into account the presence of the electron weld.

Industrial applicability

This technical solution allows the insertion of one or more defects of known shape and dimensions into one body. Thus, the resulting body may contain a whole set of defects of various characters suitable, for example, for the qualification of ultrasonic or visual or magnetic testing. These bodies are also very suitable for operator training of non-destructive measuring instruments. It is able to compete in the market mainly due to good mapping of the inserted defect. Alternatively, it can also compete on price, especially when inserting defects into larger bodies, where it can be a cheaper alternative. In the case of the insertion of more defects, it can also compete with the overall lower price compared to the purchase of more bodies with a total corresponding number of defects.

Claims (1)

PROTECTION REQUIREMENTS Test body with welded coupons, characterized in that the body (1) consists of a coupon (2) 5 by a weld and a perfect part (3) of the base material of the body (1) joined by a technically perfect weld to form an integral body (1), which is uniform in terms of non-destructive testing methods.