Standing seam profile field welding device and method

A method of welding a thermoplastic profile strip to a thermoplastic membrane, the method comprising:

• placing a thermoplastic profile strip on a thermoplastic membrane, the profile strip having a horizontal base extending longitudinally, and a first raised lip along one longitudinal edge and a second raised lip along a second longitudinal edge opposite the first edge, the first and second lips being bent substantially equal;
• directing hot air above and below a portion of the first raised longitudinal lip;
• directing hot air above and below a portion of the second raised longitudinal lip simultaneously with the hot air directed above and below the portion of the first raised lip, wherein the hot air above and below the portions of the first and second raised lips sufficiently softens the portions of the first and second lips such that gravity brings the portions of the first and second lips into contact with the membrane thereby heat-welding the portions of the first and second lips to the membrane;
• and
• advancing the hot air along the remaining length of the first and second raised lips until the entire length of the first and second lips contacts the membrane.