BS EN 16296:2021 pdf free download – Imperfections in thermoplastics welded joints一Quality levels.
The purpose of this standar(documenis to define quality levels based on typical imperfections, which might occur in normal fabrications and are classified in EN 14728 ([iJIt may be used within a quality system for the production of factory welded joints. It provides three sets of dimensional values from which a selection can be made for a particular application. The quality level necessary in each case should be defined by the application standard or the fabricator in conjunction with the user and/or other parties concerned. The level should be prescribed before the start of production, preferably at the enquiry or order stage.
For pressure pipe systemsit is recommended that at least level B be chosen.
For specific applications,_ad-d+t+ottjp.e requirements not covered by this standard m-a4iTh stringent than lrl B mighieed to be prescribed. These additional requirements and shall be defined between the contractig rtis1s quality level A.
4.2 Choice of quality level
For the choice of the quality level, the following factors, among others, shall be taken into account:
— mechanical loading (static, dynamic);
— environment (media, temperature);
— material properties (ductile, brittle);
— manufacturing conditions (workshop, construction site, welding in constrained condition);
— operating conditions;
— potentialdangerin the event of failure)
design considerations.
onomic factors are also important and should include not only the cost of welding but also the cost of inspection, test and repair.
5 Requirements for welded joints
Although this document includes types of imperfections relevant to the processes given in Clause 1. only those which are applicable to the process and application in question need to be considered.
Imperfections are quoted in terms of their actual dimensions. However, their detection and evaluation could require the use of one or more methods of non-destructive testing. It should be noted that the detection and sizing of imperfections is dependent on the inspection methods and the extent of testing specified in the application standard or contract.
The indication provided by non-destructive testing should not be used directly for the evaluation of quality levels. Therefore, it needs to be supplemented by requirements for examinations, inspection and testing.
The requirements for the above mentioned quality levellin Table 2 (B, C and D) are listed as follows:
— Heateieated tool butt welds: Table 3
— lleate4heated tool socket welds: Table 4
— Electro1uioelectrofusion socketivelds: Table 5
— Hhot gas welds: Table 6
— Extrusioxtru stun welds: Table 7
— Solvent welds in pipessolvent socket welds)Table 8.
Different types of imperfection occurring simultaneously at any cross-section of the joint may need special consideration and advice should be sought from the product manufacturer. Any two adjacent imperfections separated by a distance smalle(ess)than the major dimension of the smaller imperfection shall be considered as a single imperfection.
In certain circumstances, it is necessary to machine the completed weld. In this case, the weld shall be examined both before and after machining.