Installing a slipon flange correctly ensures leakfree connections and longterm reliability in piping systems. This guide walks through key steps, best practices, and checks so your installation meets code and performance expectations.
Use this resource to understand proper alignment, bolt tightening, and support considerations that reduce rework and onsite issues.
| Aspect | Specification | Typical Requirement | Verification Method |
|---|---|---|---|
| Flange Face Finish | Ra value | 3.2 to 6.3 micrometer | Surface finish gauge |
| Bolt Type and Material | ASTM A193 B7 or A320 B8 | Match pipe spec and temperature | Material test report |
| Gasket Selection | Spiral wound, rubber faced | Pressure class and media compatibility | Manufacturer data sheet |
| Torque Value | Based on bolt size | Follow ASME B16.5 table | Torque wrench calibration |
Preparing the Slipon Flange and Pipe
Proper setup reduces alignment issues and ensures a consistent load path across the joint.
Inspect Components
Check the flange bore, pipe OD, and gasket seating surfaces for scratches, burrs, or foreign material that could compromise sealing.
Clean and Align
Wipe surfaces with a suitable solvent, verify pipe straightness, and ensure the slipon flange slides smoothly over the pipe without forcing.
Positioning and Initial Assembly
Accurate positioning prevents uneven loading and reduces the risk of bolt hole misalignment during tightening.
Slipon Placement
Slide the flange over the pipe so the pipe end is recessed into the counterbore, maintaining the designed distance to the gasket face.
Insert Gasket
Place the gasket centrally between the flange face and the pipe end, avoiding twists that could cause leaks.
Bolting and Torque Procedure
Controlled tightening sequences preserve flange alignment and ensure even compression of the gasket.
Bolt Insertion
Insert bolts by hand to avoid cross threading, then lightly lubricate threads with a suitable nonseizing compound.
Tightening Pattern
Use a crisscross or sequential pattern and apply torque in multiple passes to the recommended values from ASME B16.5 or the project specification.
Pressure Testing and Inspection
Verification confirms that the joint performs under system conditions without visible leakage.
Hydrostatic Test
Conduct a hydrostatic test at 1.5 times the design pressure, observing for pressure drops or visible leaks at the flange face or bolt holes.
Posttest Check
After the test, confirm bolt torque, verify flange parallelism, and document results in line with quality records.
Key Takeaways for Successful Installation
- Inspect and clean all sealing surfaces before assembly
- Ensure proper pipe support and alignment prior to bolting
- Position the gasket carefully to avoid shifting during tightening
- Apply bolts in a crisscross pattern and tighten to specified torque
- Perform pressure testing and document results per project requirements
FAQ
Reader questions
How do I ensure proper alignment when installing a slipon flange?
Check pipe straightness before sliding on the flange, use alignment bars or a spool piece, and maintain consistent spacing with support blocks during assembly.
What should I do if the bolt holes do not line up after placing the gasket?
Loosen nuts slightly, adjust the flange position carefully without rotating the pipe forcefully, and verify alignment before retightening.
Can I reuse the gasket after a pressure test or maintenance?
Most spiral wound and rubber faced gaskets should not be reused because compression set and surface damage can lead to future leaks; install a new gasket.
How do I determine the correct torque for the bolts?
Follow the torque values in ASME B16.5 or the manufacturer data sheet based on bolt size, class, and material, and use a calibrated torque wrench in a crisscross sequence.