Apr 18, 2022 · HDPE Fittings. ISCO offers both molded and fabricated HDPE fittings. Our fabricated elbows, tees, reducing tees, and end caps are produced and tested in accordance with ASTM F2206 – “Standard Specification for Fabricated Fittings of Butt-Fused Polyethylene Plastic Pipe.”. ASTM F2206 places very specific requirements on fabricated fittings