Do you know the joint systems of PE pipes?
Share from BLOGPLASTICS ,September 26, 2013 By rodolfo
PE pipes must no be joined by crewing nor sticking. The systems normally used are resistance to traction and they are provided below.
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Mechanical fittings
Leaktightness is obtained by compressing a joint over the pipe, at the same time as the gripper is fixed over it to avoid the pulling out. They can be plastic or brass metallic and are often used from DN 20 to 110 mm although other kinds of melting fittings are used with higher diameters. In PE pipe filed we call it PP/PE compression fittings.
The mechanical fittings must fulfil the following functional tests:
EN 712
EN SYSTÈMES DE CANALISATIONS THERMOPLASTIQUES. ASSEMBLAGES MÉCANIQUES AVEC EFFECT DES FONDS ENTRE TUBES AVEC PRESSION ET RACCORDS. MÉTHODE D’ESSAI DE RÉSISTANCE À L’ARRACHEMENT SOUS FORCE CONSTANTE.
EN 713
SYSTÈMES DE CANALISATIONS PLASTIQUES. ASSEMBLAGES MÉCANIQUES ENTRE RACCORDS ET TUBES EN POLYOLEFINE AVEC PRESSION. ESSAI D’ÉTANCHÉITE SOUS PRESSION INTERNE DES ASSEMBLAGES SOUMIS À UNE COURBURE.
EN 715
SYSTÈMES DE CANALISATIONS THERMOPLASTIQUES. ASSEMBLAGES AVEC EFFET DE FOND ENTRE TUBES DE PETIT DIAMÈTRE AVEC PRESSION ET RACCORDS. MÉTHODE D’ESSAI D’ÉTANCHÉITE AVEC PRESSION D’EAU INTERNE AVEC EFFECT DE FOND.
EN 911
SYSTÈMES DE CANALISATIONS EN PLASTIQUES. ASSEMBLAGES À BAGUE D’ÉTANCHÉITÉ ÉLASTOMÈRE ET ASSEMBLAGES MÉCANIQUES POUR CANALISATIONS THERMOPLASTIQUES AVEC PRESSION.MÉTHODE D’ESSAI D’ÉTANCHEITÉ SOUS PRESSION HYDROSTATIQUE EXTERNE.
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Electrofusion
When the low-voltage of 40 V of electric currentpasses through themetal coils of the electrofusion fittings have, heating is produced through Joule effect that welds to the pipe the fitting. The range goes from DN 20 to 1200 mm or even higher diameters.
In the market there is a wide range of figures of electrofusion fittings like, sockets, elbows, tees, reductions, end plugs, etc.There are alsometal transitionswith or without plastic thread.In my opinion single tapping saddlesand double tapping saddles replacethe common ductile saddles, as you avoid using threads because you are using welded joints although there some people who say that the best joint is the one that doesn’t exist.
Standards about Electrofusion:
DVS 2207-1
Welding of thermoplastics – Heated tool welding of pipes, pipeline components and sheets made of PE-HD.
UNE 53394
Plastiques. Code pour l´installation et manutention de tubes en polyethylene pour la conduction d´eau sous pression. Techniques recommandées.
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Butt welding
This technique is used preferably from DN 63 mm and wall thicknesses of over 3 mm to DN 2500 mm and higher diameters. It consists in heating the ends of the pipes to be joined with a hot-plate that is at temperature of about 220 ºC and then applying a previouslytabulated specific pressurefor every kind of pipes or Butt fusion fittings (DN and PN).
Corrugated pipes are being welded to DN 3500 mm butt pipes and even to higher diameters.
Standards about butt welding:
ISO 21307
Plastics pipes and fittings – Butt fusion jointing procedures for polyethylene (PE) pipes and fittings used in the construction of gas and water distribution systems
DVS 2207-1
Welding of thermoplastics – Heated tool welding of pipes, pipeline components and sheets made of PE-HD.
WIS 4-32-08
Specification for the fusion jointing of polyethylene pressure pipeline systems using PE 80 and PE 100 materials
UNE 53394
Plastiques. Code pour l´installation et manutention de tubes en polyéthylène pour la conduction d´eau suos pression. Techniques recommandées.
Due to butt welding the Handled Fittingsare made from the pipe itself, by welding at an angle and making shapes like elbows, tees, crossheads, Y, etc., these fittings are produced in the workshop.
In small diameters, for example up to 63, the transitions to a valve, fitting or metallic pipes are often performedwith mechanical fittings and from this diameter and even higher, the transitions are made with a PE adaptor welded to the pipe and its plain flange, always including a joint to obtain the leaktightness.