Heat Fusion and Joining

Saddle Fusion

Heater Surface Temperature: Minimum 490°F - Maximum 510°F (254 – 266°C)

Heater tool surfaces must be up to temperature before you begin. All points on both heating tool surfaces where the heating tool surfaces will contact the pipe and fitting must be within the prescribed minimum and maximum temperatures. Heater tool surfaces must be clean.

Interface Pressure: Minimum 54 psi – Maximum 66 psi (372 – 455 kPa ; 3.72 – 4.55 bar)

Definitions

Initial Heat
Bead-up) The heating step used to develop a melt bead on the main pipe.

Initial Heat Force
(Bead-up Force) The force (pounds) applied to establish a melt pattern on the main pipe. The Initial Heat Force is determined by multiplying the fitting base area (in2) by the initial heat interfacial pressure (psi).

Heat Soak Force
The force (pounds) applied after an initial melt pattern is established on the main pipe. The Heat Soak Force is the minimum force (essentially zero) that ensures the fitting, heater and main stay in contact with each other.

Fusion Force
The force (pounds) applied to establish the fusion bond between the fitting and the pipe. The Fusion Force is determined by multiplying the fitting base area (in2) by the fusion interfacial pressure (psi).

Total Heat
Time A time that begins when the heater is placed on the main pipe and Initial Heat Force is applied and stops when the heater is removed. Maximum heating times are shown in Table IV for both pressure (hot tapping) and non-pressure fusion applications.

Cool Time
The time required to cool the joint to approximately 120°F (49°C). The Fusion Force must be maintained for 5 minutes on 1-1/4” IPS or 10 minutes for all other main sizes, after which the saddle fusion equipment can be removed. The joint must be allowed to cool for an additional 30 minutes before tapping the main or joining to the branch outlet. Recommended minimum cooling times are shown in Table IV.

Interfacial Area
Rectangular base fittings
The major width times the major length of the saddle base, without taking into account the curvature of the base or sides, minus the area of hole in the center of the base.
Round base fittings
The radius of the saddle base squared times pi (3.1416), without taking into account the curvature of the base or sides, minus the area of the hole in the center of the base.

Fitting Labels
The Initial Heat Force, Heat Soak Force and Fusion Force will be listed in the lower right hand corner of the fitting label for the majority of saddle fusion fittings. This eliminates the need to calculate the information in the field. For example, 80/0/40 represents the Initial Heat Force, Heat Soak Force and Fusion Force, respectively. If this information is not located on the fitting, please contact the fitting manufacturer for the correct fusion parameters.

Procedure

1. Preparation
This procedure requires the use of a saddle fusion tool. This tool must be capable of holding and supporting the main, rounding the main for proper alignment between the pipe and fitting, holding the fitting, and applying and indicating the proper force during the fusion process.

1. Install the saddle fusion tool on the main according to the manufacturer’s instructions. The tool should be centered over a clean, dry location where the fitting will be fused. Secure the tool to the main. A main bolster or support is recommended under the pipe on 6” IPS and smaller main pipe sizes.
2. Abrade the surface of the main, where the fitting will be joined, with a 50–60 grit utility cloth until a thin layer of material is removed from the pipe surface. The abraded area must be larger than the area covered by the fitting base. After abrading, clean the residue away with a clean, dry cloth.
3. Abrade the fusion surface of the fitting with 50-60 grit utility cloth. Remove all dust and residue with a clean, dry cloth. Insert the fitting in the saddle fusion tool loosely. Using the saddle fusion tool, move the fitting base against the main pipe and apply about 100 pounds-force to seat the fitting. Secure the fitting in the saddle fusion tool.

2. Heating
The heating and fusing process must be performed with accuracy and efficiency, especially when fusing to a pressurized main pipe.

WARNING: Overheating or excessive time between these two processes can have detrimental effects, including pipeline rupture.

• The heater must be fitted with the correct heater adapters.
• The heater adapter fusion surface must be between 490°F to 510°F (254°C to 266°C).
• Ensure the heating surfaces are clean.
• Determine the saddle fusion force from the fitting label or by calculation.

1. Place the heating tool on the main centered beneath the fitting base. Immediately move the fitting against the heater faces, apply the Initial Heat Force (see fitting label), and start the heat time. Apply the Initial Heat Force until melt is first observed on the crown of the pipe main (Initial Heat is the term used to describe the initial heating (bead-up) step to develop a melt bead on the main pipe and is usually 3-5 seconds) and then reduce the force to the Heat Soak Force (bead-up force) (see fitting label). Maintain the Heat Soak Force until the Total Heat Time is complete.
2. At the end of the Total Heat Time, remove the fitting from the heater and the heater from the main with a quick, snapping action. Quickly check for an even melt pattern on the pipe main and heated fitting surfaces (no unheated areas). The Total Heat Time ends when one of the following conditions are met:

i. When the Total Heat Time expires for a pressurized 1-1/4” IPS or 2” IPS main, or
ii. When a melt bead of approximately 1/16” is visible around the fitting base for a 1 1/4” IPS or 2” IPS non-pressurized main, or a larger pressurized or non-pressurized main.

3. Fusion and Cooling
Regardless of whether the melt patterns are satisfactory, quickly press the fitting onto the main pipe (within 3 seconds) after removing the heater and apply the Fusion Force (see the fitting label). Maintain the Fusion Force on the assembly for 5 minutes on 1-1/4” IPS and for 10 minutes for larger sizes. When this initial cooling time has expired, the saddle fusion equipment may be removed. Cool the assembly for an additional 30 minutes before rough handling or tapping the main.

If the melt pattern was not satisfactory or if the fusion bead is unacceptable, cut off the saddle fitting above the base to prevent use, relocate to a new section of main, and make a new saddle fusion using a new fitting.

NOTE: The Fusion Force may need to be adjusted during the initial cooling period; however, the fusion force should never be reduced.

4. Inspection
Visually inspect the fusion bead around the entire base of the fitting at the main pipe. The fusion bead should be of uniform size. The fusion should have a “three-bead” shape, which is characteristic of this type of fusion. The first bead is the fitting base melt bead. The second or outermost bead is the result of the heater tool face on the main pipe. The third bead, or center bead, is the main pipe melt bead. All beads should be of uniform size with the first and third beads approximately 1/8” and the second bead being generally smaller.

Qualification

1. Prepare at least two sample joints. The main pipe length should be a minimum of 2’ or seven times the maximum saddle fitting base dimension, whichever is greater.
2. Observe the fusion process and verify the recommended procedure for saddle fusion is being followed.
3. Visually inspect the sample joint for quality.
4. Allow the joint to cool completely (minimum of one hour). The main should not be tapped for this qualification process.
5. Prepare test straps as shown in Figure II. Cut the joint lengthwise along the main pipe and through the saddle fitting.
6. Visually inspect the joint for any voids, gaps, misalignment or surfaces that have not been properly bonded.
7. Bend each test strap 180° with the inside facing out.
8. The fusion joint must be free of cracks, voids, gaps and separations.
9. Test the other sample joint by impact against the saddle fitting. The failure must occur by either tearing the fitting, bending the fitting at least 45° by removing a section of the pipe. Failure at the fusion is not acceptable. This test is a federal requirement for qualification of fusion procedures, but is not a requirement for individual qualification.
10. If failure does occur at the weld in any of the samples, then the fusion procedure should be reviewed and corrected. After correction, another sample weld should be made per the new procedure and re-tested.

See examples of acceptable saddle fusion.
See examples of unacceptable saddle fusion.

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