{"id":646,"date":"2018-03-26T15:09:05","date_gmt":"2018-03-26T15:09:05","guid":{"rendered":"https:\/\/www.plastikcity.co.uk\/blog\/?p=646"},"modified":"2024-03-25T14:03:22","modified_gmt":"2024-03-25T14:03:22","slug":"pipe-joint-failure","status":"publish","type":"post","link":"https:\/\/www.plastikcity.co.uk\/blog\/pipe-joint-failure\/","title":{"rendered":"Pipe Joint Failure"},"content":{"rendered":"

Thousands of homes awoke recently to\u00a0<\/strong>water shortages<\/strong><\/a>, after failed pipework in the water distribution network led to hundreds of leaks throughout the network.\u00a0 Many of these leaks will have occurred where two pipes are joined to together, because of a pipe joint failure.<\/strong><\/p>\n

<\/p>\n

The blame for the failures was on the freezing weather caused by the\u00a0#BeastFromTheEast<\/a>\u00a0and the effect this has had on the water distribution network.\u00a0 Both ductile iron, and plastic pressure pipes will have been affected.<\/p>\n

It is well known that water freezing within pipe work will lead to failures once the water thaws.\u00a0 However, it is less well known that the majority of failures occur within a pipe joint failure, the place where two pipes are joined together.\u00a0 This is because this is frequently the weakest point of any pipeline installation.<\/p>\n

The plastic pipes themselves are tested extensively for hoop stress, using both c-ring tests and\u00a0hydrostatic pipe tests<\/a>\u00a0which qualify the pipe material to either PE80 or PE100 (with the number being the MPa the pipe will hold after 50 years of use.\u00a0 However, the pipe joints themselves are frequently not tested, which can lead to premature pipe joint failure, especially in harsh conditions.<\/p>\n

Plastic pipes are joined using one of two methods \u2013 either Butt fusion, or, as we will focus on here, electrofusion.\u00a0 While both methods are susceptible to pipe joint failure under freezing conditions, electrofusion welds are especially problematic.\u00a0 A report from the Water Industry in 2012 determined that as many of 20% of all electrofusion joints would fail prematurely.<\/p>\n

This is because electrofusion welds are sensitive to welding conditions.\u00a0 Any failure in the jointing process can lead to a premature pipe joint failure at a later date, especially under adverse conditions, such as ground movement, or pressures within the pipe.\u00a0 A guide to electrofusion welds can be read\u00a0here<\/a>.<\/p>\n

When a pipeline freezes it causes forces in two directions.\u00a0 Firstly, the water expands and pushes the pipe outwards.\u00a0 This force is called the \u201choop stress\u201d.\u00a0 The second force on the pipe will be a shrinking effect of the plastic itself along the length of the pipe.\u00a0 This will pull the pipe from where it is fixed, or jointed at either end, as shown in the figure below.\u00a0 In addition to this force, the coupler itself will also be shrinking, and exerting a force in the opposite direction, placing even more pressure on the joint (in the figure below the \u201cjoint\u201d is across the area with the copper pins).\u00a0 The diagram below shows these forces.<\/p>\n

\"Plastics<\/p>\n

A well made PE joint will be ductile.\u00a0 This allows the plastic to stretch under load without cracks or failures.\u00a0 A poorly made PE joint however will fail in a brittle manner, causing cracks and failed pipe lines.<\/p>\n

Quality control of pipeline installations should incorporate strict procedures, non destructive testing and destructive testing of sample fittings to ensure procedures are being followed.\u00a0 These quality protocols can ensure that a plastic pipeline can avoid failures during extreme conditions or extreme weather events, ensuring no plastic pipe joint failures.<\/p>\n

\"Impact<\/p>\n

Impact Solutions<\/em>
\n+44 (0)1324 489 182<\/em>
\nWebsite<\/em><\/a>
\nEmail<\/em><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Thousands of homes awoke recently to\u00a0water shortages, after failed pipework in the water distribution network led to hundreds of leaks throughout the network.\u00a0 Many of these leaks will have occurred where two pipes are joined to together, because of a pipe joint failure.<\/p>\n","protected":false},"author":101012,"featured_media":647,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[261,280,282,281],"class_list":["post-646","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-plastikcity-blogs","tag-impact-solutions","tag-material-testing","tag-pipe-joint","tag-pipework","post-preview"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.plastikcity.co.uk\/blog\/wp-json\/wp\/v2\/posts\/646","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.plastikcity.co.uk\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.plastikcity.co.uk\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.plastikcity.co.uk\/blog\/wp-json\/wp\/v2\/users\/101012"}],"replies":[{"embeddable":true,"href":"https:\/\/www.plastikcity.co.uk\/blog\/wp-json\/wp\/v2\/comments?post=646"}],"version-history":[{"count":1,"href":"https:\/\/www.plastikcity.co.uk\/blog\/wp-json\/wp\/v2\/posts\/646\/revisions"}],"predecessor-version":[{"id":2355,"href":"https:\/\/www.plastikcity.co.uk\/blog\/wp-json\/wp\/v2\/posts\/646\/revisions\/2355"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.plastikcity.co.uk\/blog\/wp-json\/wp\/v2\/media\/647"}],"wp:attachment":[{"href":"https:\/\/www.plastikcity.co.uk\/blog\/wp-json\/wp\/v2\/media?parent=646"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.plastikcity.co.uk\/blog\/wp-json\/wp\/v2\/categories?post=646"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.plastikcity.co.uk\/blog\/wp-json\/wp\/v2\/tags?post=646"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}