DERATING REQUIREMENTS FOR FITTINGS

Size: px

Start display at page:

Download "DERATING REQUIREMENTS FOR FITTINGS"

Virgil Eaton
5 years ago
Views:

1 Suite 2, Level 7, 62 Pitt Street Sydney NSW 2000 Phone: (02) Fax: (02) Internet: Industry Guidelines DERATING REQUIREMENTS FOR FITTINGS Issue 5.01 Ref: POP006 5 December, 2003

2 Disclaimer PIPA makes no warranty or representation regarding the information, opinions and recommendations contained in the Guidelines. Users of the Guidelines are advised to seek and rely upon their own professional advice and assessment of the matters contained in the Guidelines and to not rely solely on the Guidelines in relation to any issue that may or might risk any loss. In addition, PIPA excludes: (a) (b) all conditions, warranties and terms implied by statute, general law or custom except where exclusion would contravene any statute; and all liability to any user of the Guidelines for consequential or indirect damages, or any other form of compensation or relief whatsoever for any acts or omissions of PIPA, arising out of or in connection with the use of the Guidelines irrespective of whether the same arises at law, in equity or otherwise. PIPA s liability to any user of the Guidelines for any breach of a non-excludable condition or warranty is limited at PIPA s option, to any one of resupplying, replacing or amending that part of the Guidelines in respect of which the breach occurred. POP006 Issue 5.01 Page 2

3 DERATING REQUIREMENTS FOR FITTINGS The PIPA Technical Committee has prepared this publication as a guide to the derating of Polyethylene fabricated and moulded sweep bends and Tees, for use with polyethylene pipe made to AS/NZS The Deratings are taken from the German Plastics Welding Institute recommendations, and are considered to be conservative. However it is considered necessary to use this conservative rating on these items, as the consequential costs involved with a failure of a fitting can be very high and must be avoided. 1 SCOPE These guidelines cover pressure fittings manufactured from Polyethylene which are not covered by AS 1460 or AS/NZS 4129 or an equivalent International Standard, and which are intended for use with polyethylene pipes made to AS/NZS COMPOSITION 2.1 PE Compounds Polyethylene compounds used in the manufacture of fittings shall comply with AS/NZS 4131 or the relevant International standard. 2.2 Polyethylene Pipes Pipes used in the manufacture of fittings shall be manufactured from the nominated grade and type of polyethylene, and shall comply with AS/NZS DESIGN AND DIMENSIONS 3.1 General The supplier shall be responsible for the design of the fitting and shall designate the maximum working pressure for the fitting at 20º C. 3.2 The supplier shall provide substantiation of the designated working pressure and fitness for purpose of the fitting if required. POP006 Issue 5.01 Page 3

4 4 PERFORMANCE DERATING FACTORS 4.1 Unless performance and test Data is provided to support alternative values, the following weld factors and derating factors should be used. Equal Tees 0.6 Reducing Tees ( dia. branch < 0.33 * dia. Basic pipe ) 0.8 ( dia. Branch > 0.33 * dia. basic pipe ) 0.6 Bends Any angle above Radius 1*D. 1.0 Fabricated Sweep bends (No reduction in wall) 2*dia 0.9 < 2*dia. 0.8 (Wall on inner radius to be +10% of min. pipe wall to AS 4130, Outer radius wall to be within 5% of min. pipe wall to AS 4130 ) Segmented bends radius 1*dia. To 1.5 * dia Manufacturing Factors Moulded 1.0 Butt Welded 0.9 Socket / Mirror Welded 0.8 Extrusion Welded 0.6 Saddle Fusion 1.0 No other welding method is acceptable. 4.3 Calculation of Factors The nominal strength of the fitting is derated by multiplying the rating by the geometry Factor and the Manufacturing Factor. 4.4 Spigot ends The outside diameter of the spigot ends shall meet the requirements of AS/NZS For a length of one Diameter from the end. The Wall thickness at the end shall also meet the requirements of AS/NZS 4130 for the grade of pipe to be connected to the fitting. The free length of the spigot ends shall be suitable for the nominated jointing method. POP006 Issue 5.01 Page 4

5 4.5 Manufactured Bends The angle of any Bend shall be within +- 5 o of the specified angle. 4.6 Backing Flanges Unless otherwise specified by the client, backing flanges shall comply with the nominated table of the PIPA Industry Guideline on Backing Flanges. 5 FREEDOM FROM DEFECTS 5.1 Fittings shall be examined for defects by visual inspection in the first instance, or by any other inspection method if required. 5.2 Fittings shall be smooth and clean with no grooves or blisters or other visible defects on the surface. 5.3 There shall be no Cavities, voids or inclusions in the fitting body, or in any welded part of the fitting. 5.4 Defective fittings cannot be repaired and re-supplied. Unless specifically authorised by the client in writing. 6 WELDING 6.1 All welding carried out on fittings must be undertaken by an accredited welder, and the weld must carry his stamp for permanent identification. 7 TESTING 7.1 OIT Testing All fittings shall have an Oxidation Induction Time of 20 minutes or better, when tested by ISO/TR 10837, at a test temperature of 200 º C. 8 MARKING 8.1 All fittings shall be clearly marked with at least the following information. a) Manufacturers name or Trade mark b) Identification of the material Type c) Pressure Class as nominated by the manufacturer based on this guideline d) Nominal size and SDR of the pipe for which the fitting is intended e) Code for traceability of manufacturing Date or Batch. POP006 Issue 5.01 Page 5

Large polyethylene pipes

Large polyethylene pipes Krah pipes for pressure application Krah-Pipes are large polyolefin pipes up to an internal diameter of 4000mm and a maximum solid wall thickness of 200mm. The preferred jointing