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WIS 4-41-01 Issue 2 Specification for flexible couplings for gravity sewerage and drainage pipes

Replaced by:

It is believed WIS 4-41-01 Issue 2 February 1993 was withdrawn once BS EN 295-4 Vitrified clay pipe systems for drains and sewers. Requirements for adaptors, connectors and flexible couplings was published in 1995.  BS EN 295-4 was subsequently revised in 2013.

However, see the Note below for the complex situation regarding the interplay between the statuses of EN 295 -4 and the EN 16397 series of standards.


In recognition that it would be much better to have a single standard for flexible couplings of all types, since they are widely used across different pipe material types and sectors, CEN Technical Committee TC165 Wastewater Engineering decided to write a universal standard for flexible couplings with a plan to remove the overlapping aspects of EN 295-4 after a short period of coexistence. The first part of this plan was fulfilled by the publication of BS EN 16397-1: 2014 Flexible couplings: Performance requirements and BS EN 16397-2 2014 Flexible couplings: Characteristics and testing for metal banded flexible couplings, adaptors and bushes.

However, EN295-4 is a harmonized standard and was written under the rules that applied from the Construction Products Directive (CPD).  Accordingly, manufacturers can use compliance with its “essential requirements” as a means of obtaining a CE mark. The publication of the EN16397 series in 2014 occurred soon after enactment of the Construction Products Regulations (CPR) with different assessment rules, so it failed its assessment by the Commission and could not be used as a basis for citation in the Official Journal of the European Union (OJEU). Thus, TC165 could not revise EN295-4 to remove duplication without leaving all future CE marking of flexible couplings reliant on the use of a withdrawn standard. Attempts over the intervening period to amend EN16397 to comply with the Commission’s interpretation of the CPR rules while still satisfying the market requirements have met with no success as there are fundamental incompatibilities.

Discussion on this topic in TC 165 focussed the attention of the CEN-CENELEC Management Centre (CCMC) on the current overlap of the scopes of the harmonized EN295-4 and the EN16397 series, which breaches CEN standardization rules. CCMC claimed that steps must be taken to withdraw the EN16397 series as it should not have been published in 2014.  So, unless CEN/TC 165 can find a way to bypass the edict to withdraw EN16397, couplings for all pipes irrespective of material may have to comply with a standard focussed on clay. It may also be illegal under single market rules to sell them in Europe if they don’t.

However, the Board now understands that instead of simply withdrawing the EN16397 series as instructed by CCMC, TC165 has decided to revise it with the intention of complying with harmonization rules which would then allow it to replace EN295-4 as originally planned and provide a new route to CE marking. CCMC has been silent on the matter since their original request so it is assumed they are content that TC165 is actively solving the conflict. The principal authors within the TC165 project task group for this revision are both UK experts – and members of the BSI mirror committee to TC165 (B/505/1).

Given that the EN16397 series has not actually been withdrawn and that EN295-4 remains a harmonized standard, it would be unwise for WIS-4-41-01 to coexist in a form that organizations subject to the successor to the Construction Products Directive (e.g. Water & Sewerage Companies) might cite it. However as there is a risk that EN16397 may still be withdrawn at some stage it is considered helpful to keep the WIS in an accessible form with this note indicating that it was withdrawn following the publication of EN295-4 and the EN16397 series. It could then either be updated & restored to a ‘current’ status or remain as an ‘archived’ document to provide a historic reference to components that were certified as complying with it.

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