BS EN 16296:2012 pdf download – Imperfections in thermoplastics welded joints — Quality levels
This European Standard provides quality levels for imperfections in thermoplastics welded joints. It applies to material thickness above 2,0 mm. Three quality levels are given in order to permit application for a wide range of welded fabrication. They are designated by symbols B, C and D, where B is the most stringent. The quality levels refer to production quality and not to the fitness-for-purpose (see 3.2) of the manufactured product.
This European Standard applies to the following thermoplastic materials:
and to the following welding processes:
Heated tool welding;
Hot gas welding using filler rod only;
2 Normative reference
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references,the latest edition of the referenced document (including any amendments) applies.
EN 1 4728, Imperfections in thermoplastic welds — Classification
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply
description of the qualities of a weld on the basis of type and size of selected imperfections
ability of a product, process or service to serve a defined purpose under specific conditions
4 Quality levels
Three quality levels are defined as B, C and D in order to permit application for a wide range of welded fabrications (see Table 2).
The purpose of this standard is to define quality levels based on typical imperfections, which might occur in normal fabrications and are classified in EN 1 4728. It 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 specific applications, additional requirements not covered by this standard may need to be prescribed. These additional requirements shall be defined as 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);
potential danger in the event of failure.
5 Requirements for welded joints
The requirements for the above mentioned quality levels (B, C and D) are listed as follows:
Heated tool butt welds: Table 3;
Heated tool socket welds: Table 4;
Electrofusion welds: Table 5;
Hot gas welds: Table 6;
Extrusion welds: Table 7;
Solvent welds in pipes: 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 smaller 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.