Below is a detailed Method Statement For Field Joint Insulation of Pre Insulated Chilled Water Pipe. Following tools and equipment shall be arranged before starting the pipe joint insulation process.
- Rayjoint, S113 sealing strips
- Propane gas bottle,regulator and gauge,hose and torch
- Abrasive tape
- Marker,measurement tape.knife
- PE Cleaner + Dry cleaning rags
- Heat shields & Foaming Plugs
- Gloves & Safety Goggles
- Pressure test equipment
- Standard safety equipment as prescribed by local regulations.
PREPARATION BEFORE PIPE JOINT INSULATION
- Slide the Ray joint over pipe end before welding,remove plastic bag just before installation of the Ray joint
- If Needed keep the plastic bag as sun protection.
- The PE jacket and Ray joint Should be dry and free of foreign materials such as mud,oils and greases.If necessary,clean with PE Cleaner.
- Mark the position of the ray joint centered over the joint area.The maximum cutback should be less than 460mm. A=(700 mm – cutback)/2
- Abrade the PE jacket .that will be covered by the Ray joint,on both sides adjacent to the cutback.
PIPE JOINT INSULATING PROCEDURE
- Measure the circumference of the PE Jacket and cut two sealing strips long enough to allow for overlap in accordance with the table below.
- Dry the pipe ends with a torch.(30 Deg- 40 Deg C)
- Keep the flame pointed away from the foam.
- Apply the sealing strips on the pipe ends.The mastic strip edge should be next to the marks leave the release plastic on the sealing strips.
- SEALING STRIP CUT LENGTHS.
- 90mm to 200mm OD – Pipe circumference + 25 mm
- 225mm to 315mm OD – Pipe Circumference +50mm
- > 315 mm OD – Pipe Circumference + 75mm
- In the overlap area ,remove the release plastic between the two layers and push the mastic overlap together,Re apply the release plastic over exposed mastic.
- Two spacers are used per pipe end and are positioned around the circumference at 11 and 1 o’ clock as possible to the PE Pipe end.
- In case of wide cutback,the spacer might be positioned on the mastic but again close to the pipe end.
- Slide the RayJoint carefully over the sealing strips and center it over the joint.The amount of release plastic visible should be equal on both ends of the RayJoint. Take care that the RayJoint overlap is not located on top.
- Make the edges of the pipe ends on the Ray Joint and Make additional indications for the foaming holes on distance from the PE jacket edge.
- Drill one small foaming hole on the position as indicated by the marks,to allow air to escape during installation.Drill size:6-10mm.(CAUTION:DO NOT DRILL HOLE IN THE Ray Joint overlap area.
- Remove the release plastic from both sealing strips.During removal of the release plastic make sure that foaming holes are located on top of the RayJoint. Be careful to keep the RayJoint in place centered over the joint.
- Wrap the heat shields tightly around the PE jacket next to the RayJoint. Check that they will not be covered by the RayJoint when it shrinks on to the pipe.Wrap a second pair of heat shields tightly around the Ray Joint. These should be Located next to the pipe end marks.
- Use a soft flame to give the heat sufficient time to penetrate the PE jacket.Move the flame around the circumference in close proximity to the heat shields.Carry on for about two minutes making sure not to burn the surface.
- Move over to the other end.carryout the same procedure and then return to the first end.
- Alternate repeatedly until a shrink reaction visible continue shrinking until the Ray Joint ends are in complete contact with the PE jacket. Post heat the RayJoint ends to complete the Installation.
- Installation is complete when no upstanding ends are visible Remove the heat shields.
SHRINKING RAYJOINT
- Start position ; Start chrono and check time how long it takes to shrink .
- Half way shrinking : When the Ray joint ends touch the pipe over the complete circumference the shrinkage is half way. Stop the chrono and check the time it took to shrink half way.
- End position; Continue to shrink for the same amount of time to shrink the RayJoint completely. The shrinkage is completed.