DESIGN GUIDELINES FOR COMPLETE SYSTEM
For every application received from a customer, we must have the Application RFI Questionnaire and the relevant assembly drawings of the pipeline. We design the pipe class and recommend the complete solution.
The detailed assembly drawing of the proposed solution is sent to the client for approval. We transform the approved version into parts drawings and prepare a price quotation.
1.1 If possible, use Pexgol straight pipes with a natural bend (see Natural bending radius). Pexgol pipes come in straight sections in maximum length of 11.8 meters. They are available with one or two flared ends and flanges. If you have to bend a pipe with a longer length, order two sections and make a longer pipe by connecting it with a reinforced electrofusion coupler. Always select the length of the two sections so that the electrofusion coupler is not in the exact location of the bend.
When straight pipe sections with the natural bend is not an option, use Prefabricated Pexgol elbows 3XD or 1.5XD. Please note that our 1.5xD elbows are significantly longer than the carbon steel 1.5xD elbows. 3XD elbows are recommended rather than 1.5XD since 3XD elbows reduce head losses and abrasion rate. Other non-standard angles are available by special order.
Elbows and natural pipe bends must be fixed with fixpoint clamps before and after each elbow. For pipe diameters of 280mm and larger, the natural pipe bends should be supported in the centre, in addition to the two fixpoints. If there is not enough space for Pexgol elbows, you can specify Pex-lined steel elbows.
The following items, in addition to straight pipe sections and elbows, can be supplied from Pexgol material: concentric or eccentric reducers and instrumentation Tees.
- Pex-lined steel fittings
- Components in the line which are not straight pipes or elbows including steel Tees, laterals, and others can be designed as Pex-lined steel fittings. Choose standard items from our Fittings Catalog. However, if you find that you need to make a non-standard item with longer or shorter legs, make your selection and ask Golan for approval.
- Maximum length of any item is approx. 2000mm x 2000mm.
- The standard items come with fixed flanges.
- When Pex-lined steel fittings are connected to Pexgol pipes or elbows, the ID of the Pex-lined steel fittings can be larger than the ID of the Pexgol pipe with the same flange size. In order to match up their ID, smaller –size fittings with the same flange sizes as the flanges of the pipes can be used.
- Expansion joints & Omega loops
- Expansion joints and Omega loops are not necessary in a Pexgol system. However, expansion joints might be needed when connecting a few Pex-lined steel fittings.
- Influence of temperature changes on pipeline length
- The length of Pexgol pipes can be changed by 0.3% due to a temperature change of 20°C, meaning 3mm for every 1 meter.
- When installing a straight Pexgol pipe section between two steel flanges, take into consideration the thermal expansion of the Pexgol pipe.
- Field welding
- The actual length of the pipe can be different than the designed length due to production tolerances and temperature changes.
- Field welds should be included in the design in order to compensate for the deviation of the actual length of the pipe during the installation from the designed length.
- This is very important in case of pipes and elbows with flared ends. It is a good practice to design some pipe ends with mechanical couplers.
- When using only mechanical connectors, design some of them so that the final pipe length can be adjusted on site.
- Fixpoints must be designed before and after each fitting (for example, flared end connection) as specified in our engineering guide.
When designing Pexgol pipes and fittings, the designer can utilize the flexibility of the Pexgol pipes & elbows. However, Electrofusion and Mechanical fittings should be regarded as rigid items.
Special care should be exercised in order to prevent excessive bending moment from being exerted on the fittings due to forced installation.
Specifying the length of the Pexgol straight sections and elbows as separate items is acceptable after the design has been completed and approved by the designers and by Pexgol. It is a good practice to specify a longer section to allow for measuring inaccuracies other possible errors.