e No part of this standard may be reproduced without the prior permission of DIN Deutsches Institut für Normung e.V., Berlin. In case of doubt, the. Buy DIN POLYETHYLEN COATINGS OF STEEL PIPES AND FITTINGS – REQUIREMENTS AND TESTINGS from SAI Global. DIN () Polyethylene coatings on steel pipes and fittings – Requirements and testing. Be notified when this Standard is updated or amended – Add.
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DIN PE coatings In case dln doubt, the German-language dn shall be considered authoritative. The previous edition of DIN was published in and could not be revised for a long time because work was being carried out on the European standards project EN The present edition of DIN not only covers fields of application that are not dealt with in DIN EN ISO and DIN ENit also takes into consideration the current state of the art, not only as regards the tests and test frequencies specified here for the first time, dn also as regards various product requirements.
The option of agreeing on design temperatures for different dij of coating, and of agreeing on a special, greater coating thickness have been maintained here. A 1 mm thickness is necessary for the polyethylene coating layer in terms of corrosion protection, while the remaining layer thicknesses serve to improve resistance to mechanical loading.
A check of the effectiveness of stabilizing agents by controlling the MRF before and after extrusion has now been specified. The test of the degree of cure of the epoxy resin coating by means of DSC measurement is also new, as is the cathodic disbondment test, which is frequently required at international level. Extensive investigations and practical experience have shown that, regardless of the manufacturing method, disbondment of damaged polyethylene coatings can occur depending on the salinity of the soil water and the extent of cathodic polarization.
However this involves neither an increased risk of corrosion underrusting nor an increase in the protective current density requirement in cathodic corrosion protection.
The cathodic disbondment test thus does not serve to evaluate the boundary phase reaction in the case of damaged coatings, which is unavoidable in practice, but is primarily a means of assessing the boundary areas between the epoxy resin layer and the steel substrate.
This test has therefore been specified here to evaluate surface preparation. For single-layer sintered polyethylene coatings, it is difficult to achieve the required peel strength without suitable surface preparation, and so the cathodic disbondment test is not required for single-layer sintered polyethylene coatings.
The peel strength requirements have been adapted to the production methods commonly used today. The differences between sintered and extruded by sleeve extrusion or sheet extrusion coatings have been taking into consideration.
Experience gained in the transport and laying of pipes and pipelines with polyethylene coatings has shown that a high bond strength is necessary to reduce possible mechanical damage to the pipes. Bond strength is not a significant factor with regard to the protection the coating provides against corrosion, as long as the thickness and dun of the coating meet the requirements of this standard and as long as the coating is undamaged and is in good contact along the entire pipe length.
Today, findings confirm that the testing of new materials exposed to wetting agents at high temperatures does not have any significance as regards ageing-related stress cracking behaviour.
Relevant changes to the materials during operation, such as a reduction of elongation-at-break and tear strength values — and thus changes to the fracture properties of the polyethylene — are not well-described in short-term tests involving exposure to wetting agents even at higher test temperatures.
The saponification of adhesive components, and 3060 stress crack formation due to the effects of wetting agents, are not possible when an epoxy resin primer di adhesive copolymers are used in a threelayer coating system. This also applies for single-layer sintered polyethylene coatings. For this reason, a wetting agent test is not specified in this standard. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights.
Previous editions DIN The present standard specifies requirements for coatings that are applied to longitudinally or spirally welded or seamless steel pipes and fittings used for the construction of pipelines for conveying liquids or gases. Applying this standard ensures that the PE coating provides sufficient protection against the mechanical, thermal and chemical loads occurring during operation, transport, storage and installation.
DIN EN ISO specifies requirements at international level for three-layer extruded polyethylene- and polypropylene-based coatings for steel pipes for petroleum and natural gas pipeline transportation systems.
For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document including any amendments applies. Determination of gel time of thermosetting coating powders at a given temperature DIN EN ISOPreparation of steel substrates before application of paints and related products — Visual assessment of surface cleanliness — Part 1: The epoxy resin primer is applied as a powder.
The adhesive can be applied either as a powder or by extrusion. For extruded coatings a differentiation is made between sleeve extrusion and sheet extrusion. Sintered polyethylene coatings are single- or multi-layer systems. The polyethylene powder is fused onto dkn pre-heated component until the desired coating thickness is reached.
The coating type is to be stated in the purchase order. Other design temperatures may be agreed between the purchaser and the coater. Table 1 — Types of coating Type Design temperatures for sintered polyethylene coatings Design temperatures for extruded polyethylene coatings Area of application N from? Any deviating requirements of the purchaser regarding vin materials to be used shall be subject to agreement.
Blast cleaning and any necessary subsequent work shall not result in the reduction of the minimum wall thickness specified in the technical delivery standards for the steel pipe. Residual abrasive dust shall be removed prior to coating.
Table 2 gives an overview of the necessary information to be included in the delivery documents and technical data sheets.
This data relates to the raw materials and can differ from the values for the applied coating. Information as to whether specimens were compression-moulded, sintered or extruded is also required. The minimum layer thickness is 60?
DIN 30670 seamless coating pipe with Polyethylene coatings
The minimum layer thickness is ? The peel strength requirements vary depending on whether the adhesive was applied as a powder or was extruded. The coating is to be cooled after application to avoid unwanted deformation during transport. Depending on the nominal size, there are different minimum values for the normal total coating thickness n. Minimum layer thicknesses are given in Table 3 below. rin
The total coating thickness coating system thickness is to be determined in accordance with Annex A. The table in this translation is the corrected version which will be published in a Corrigendum to the German version of this standard. For three-layer coatings, the epoxy resin and adhesive layers at the pipe ends shall be removed to at least 80 mm from the welding bevel. Cin not less than 20 mm strip 3060 epoxy resin or epoxy resin and adhesive should extend from the cutback of the polyethylene coating.
Other requirements may diin agreed upon request and at the time of ordering. For single-layer sintered coatings the level of adhesion of the polyethylene 3060 the steel substrate shall be assessed. The surface roughness Rz shall be between 40? After abrasive cleaning the quality of the pipe surface shall be visually checked. Prior to coating application, the metal surface of the steel pipe shall be free of all contaminants and deleterious matter such as dirt, oil, grease, weld beads, etc.
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The same applies to the relevant extrusion line parameters. The appearance of the applied intermediate layers shall be regularly inspected. After it has cooled, the appearance and continuity of the coating system shall be visually assessed along the entire pipe length.
The coating shall be of a uniform colour, have a smooth di and be free of holidays and other defects detrimental to the quality of the coating.
A differentiation is made between production control and system testing. In system testing the required material properties and functional requirements on the coating components as in this standard are determined and documented. System testing is to be carried out every three years on each coating composition and for each coating method.
DIN coated steel pipe with Polyethylene coatings
Production control is assured by the coater. Production controls are to be carried out by the coater or a recognized materials testing body. If the material requirements specified in this standard are not met during a test carried out as part of production control, this rin is to be repeated with twice the number of specimens.
If the requirements are still not met, the production lot shall be blocked. Other documents may be agreed. Other test sequences can be agreed.
For sintered coatings these coating properties are to be confirmed during system testing. For sintered coatings the total defect area shall not exceed 10 cm?
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The coating materials that are used for repairing defects shall satisfy two conditions. They shall be suitable for protecting onshore and offshore pipelines under the required service conditions e. They shall be compatible with polyethylene coating fin has been applied. After application the repair shall be verified in accordance with Annex E. The repair shall be 3670 from holidays. Alternative provisions for repairs may be agreed. Marking shall be carried out using a suitable method such dim stencil painting or printing, and shall be durable and legible.
The use of steel ropes, slings or any other equipment which could damage the coating or pipe ends is prohibited. During transportation, measures shall be taken to prevent damage to the steel pipes and fittings or to the coating. After delivery, pipes intended to be stored outdoors for a long period shall be protected from the effects of ultraviolet radiation. The thickness of single layers and the total coating thickness shall be determined.
The thickness of the epoxy resin primer and PE adhesive layer shall be determined on at least three representative points on the surface distributed equally along the pipe circumference.
The instrument shall be suitable for and calibrated for the coating thickness range to be measured. On each pipe being inspected carry out at least 12 measurements. For submerged arc welded pipes, an additional four thickness measurements shall be taken on the weld area. The measurements shall be made at points distributed along four equally spaced longitudinal lines at the intersection with three equally spaced circumferential lines and at a distance of at least mm from the end of the coating.
The method shall be carried out as in these standards unless there are deviating specifications in this Annex. The sample shall not have any PE adhesive residues. The peak occurring further along the curve characterises the uncured portion of the material.
The difference of the two fin transition temperatures should comply with the specifications of the raw material manufacturer. The section should not be taken from the weld area. Drill a 6 mm hole through the coating down to the steel substrate. Then, centre the electroyte cell with the electrodes around the hole.
Using a suitable sealant, form a seal between the electroyte cell and the polyethylene coating. Add distilled water to make up for loss of electrolyte during the test period.