Weld fitting

A heat-weldable weld fitting, comprising:

• a cylindrical fitting main body portion having:
• an outer periphery including a first end portion and a second end portion opposite from the first end portion, and a middle section between the first end portion and the second end portion that is configured to be clamped by a clamp portion of a welding apparatus, the first end portion and the second end portion being arranged along an axial direction of the fitting main body portion, and the first end portion being configured to be heated by a heater and is welded to an end portion of another weld fitting,
• positioning scales formed at equal intervals in a peripheral direction of the second end portion of the outer periphery of the fitting main body portion, the second end portion being configured to be not clamped by the clamp portion,
• wherein the positioning scales are configured to define an angular position of the weld fitting relative to the welding apparatus at the time of welding the first end portion to the first end portion of another weld fitting,
• wherein each positioning scale matches with a reference mark provided on the clamp portion of the welding apparatus,
• wherein the positioning relationship is defined by the weld fitting fully overlapping another weld fitting, and
• wherein no positioning scale is provided at the end portion of the weld fitting.