Patent ID: 7011779

Claim:
A method of constructing a double wall tank having an outer tank of steel and an inner tank of thermoplastic material, said outer tank having an inner surface with first areas and a second area, said first areas being located adjacent to each of at least two fittings that are separate and apart from one another, said second area being a remainder of said inner surface that is not said first areas, said method comprising applying bonding material to said first areas and not to second area, inserting thermoplastic material in powder form into said outer tank through an opening for a fitting, inserting a plug in each opening, said powder including mold release material, subjecting the outer tank to heat and rotating said outer tank to mold said inner tank within said outer tank, cooling said tanks to form said double wall tank having an inner wall of said thermoplastic material that is bonded by said bonding material to said first areas and not bonded to said second area, removing each plug and cutting an opening through said inner wall of thermoplastic material at each opening.