Saddle fusion is used to join service saddles, tapping tees and branch saddles to a Polyethylene pipe main. When joining a fitting to a pressurized main, the possibility of a main pipe blowout increases when internal main pipe pressure is higher or when the temperature of the main pipe is elevated.
When joining saddles to a pressurized gas main, gas main pressure must not exceed limits specified in Federal regulations.
Saddle FUSION PROCEDURES
- A saddle fusion tool (Sidewinder or similar) with appropriate clamps for the main pipe and saddle fitting. A main bolster is required for 6-inch and smaller main pipes. The saddle fusion unit must have a pressure gauge which indicates the force applied when the saddle is pressed against the main pipe.
- A heating plate fitted with the correct convex and concave heater adapters. Both serrated and smooth heater adapters are acceptable.
- 50 to 60 abrasive utility cloth (not sandpaper). Replace utility cloth often.
- Timing equipment is required when fusing to 2 inch and smaller main pipes.
Fit the heating tool with the correct convex and concave heater adapters for the pipe’s main size and the fitting to be joined. Make sure the heater faces are clean. Heating tool surfaces must be at the specified temperature at a MINIMUM 490 DEGREES F – MAXIMUM 510 DEGREES F. All points on the heating plate must be within the specified temperatures before you begin. Heater plates should be checked periodically with a pyrometer in all points where the heating plate comes in contact with the pipe.
Incorrect temperature may result in a blowout of the main pipe when joining fittings to a pressurized main.
Determine the correct fusion pressure for the fitting to be fused. This is normally printed on the fitting label in the lower right hand corner of the label For example, 80/0/40 would give the Initial Heat Pressure/ The Heat Soak Pressure and the Fusion Pressure in that order. If that information is not on the fitting contact the fitting manufacture for the correct fusion pressures. The interface pressure for saddle fusion is 30 psi and fusion pressure can be calculated using the length of a rectangular base, X, the width of the base, minus the area of the hole in the middle. For a round base fitting, the radius of the saddle base squared times rr (3.1416), minus the area of the hole in the center.
SADDLE FUSION PROCEDURES
Determine the area of the main pipe the fitting is to be joined. Center the saddle fusion tool at the location the saddle is to be fused. Install the fusion tool on the main pipe according to the tool manufactures instructions. Make sure the fusion tool is secured to the main pipe. A bolster or support is required on main pipes under 6 inches in diameter.
Sand (ABRADE) the pipe main where the fitting is to be joined plus about ½ inch around the area with a 50-60 grit utility cloth, (NOT SANDPAPER), and the fusion surface on the base of the pipe fitting. It is necessary to remove a thin layer of material from both surfaces. Clean the area with a clean, dry cloth or paper towel. Do not touch the abraded surface with your hands.
Clamp the fitting in the saddle fusion tool. Move the fitting against the pipe main and apply 100 psi to seat the fitting against the pipe main. Wiggle the fitting to make sure that it is completely seated against the main pipe.
HEATING AND JOINING
Center the heater beneath the fitting base, quickly bring the heating tool against the pipe main, move the fitting against the heating tool and apply bead-up force. This entire procedure should take less than 5 seconds.
Heating Bead-up Force. During bead-up, pressure is applied to create an initial melt pattern on the main pipe and the fitting base. Bead-up ends when melt is visible at the top-center of the main pipe on both sides of the heater, and pressure is reduced to zero. Normal time for bead-up force is 3-5 seconds but not to exceed 1/3 of the total heat period.
Heating Force. The heat soak pressure is zero. During the heat soak period the fitting, the heater and the pipe main are held together without any pressure or force.
Heating Time. Heating time begins when the heater is first applied to the main and ends when the heater is removed from between the pipe main and the saddle fitting. When sidewall fusion is performed on 2 inch and smaller mains, a stopwatch or watch with a second hand is required for measuring heating time. (Never exceed maximum heating time as blowout may occur when saddle fusing to a pressurized main.)
Heater removal. When the heating time ends quickly separate the heating tool from the main pipe and the fitting (3 seconds) move the fitting against the main pipe and apply joining pressure.
Joining Force. Joining force is applied immediately after the heater is removed from between the fitting and pipe main. Joining pressure is ½ the bead-up pressure. Joining pressure must be maintained for the entire time of the first cooling period. (Reducing joining pressure during the initial cooling period may result in a blowout of a pressurized main pipe).
Minimum Cooling Time. Cooling time is broken down into 2 periods. Joining Pressure must be maintained during the first cooling period. (Failure to maintain fusion pressure during the first cooling period may result in a blowout of a pressurized main pipe).
|MAIN SIZE||MAXIMUM HEATING TIME||INITIAL COOLING TIME||SECOND COOLING TIME|
|1-1/4’ – 1-1/2” IPS||15 SECONDS. OR WHEN 1/16” BEAD IS VISIBLE AROUND FITTING BASE||5 MINUTES||30 MINUTES|
|2 “ IPS||35 SECONDS. OR WHEN 1/16” BEAD IS VISIBLE AROUND FITTING BASE||10 MINUTES||30 MINUTES|
|3 “ IPS||STOP HEATING WHEN 1/16” BEAD IS VISIBLE AROUND FITTING BASE||10 MINUTES||30 MINUTES|
|4 “ IPS||STOP HEATING WHEN 1/8” BEAD IS VISIBLE AROUND FITTING BASE||10 MINUTES||30 MINUTES|
Inspect. Visually check the fusion bead around the entire fitting base where it joins the main pipe. The fusion bead should have a uniform size with a 3-bead shape. The first and third beads should be about the same shape and size around the fitting base. The second bead is normally smaller and also should be uniformly sized around the fitting base.
The fitting label should have the fusion pressures printed on the lower right hand corner of the label. If the pressures are not available on the label, contact the fitting manufacturer for the correct pressures.
BEAD-UP FORCE/PRESSURE IS THE FIRST NUMBER ON THE FITTING LABEL.
Saddle FUSION PROCEDURES
|Beads too small||Not enough heating – Not enough joining pressure.|
|Beads too large||Too much heating time – Too much pressure.|
|One bead larger than the other||Misalignment – Loose heating tool adapters – Worn equipment – Saddle slipped in clamp.|
|Non-uniform bead size||Misalignment – Loose heating tool adapters – Worn equipment – Heating tool at the wrong temperature – Fitting not secured.|
|No center-bead||Not enough joining force.|
|Main pipe blowout||Overheating – Wrong heating tool adapters – Wrong temperature Too much time to start heating – Too much time to remove heating tool and join|