Joint construction for lined equipment

A wall assembly comprising:

• (a) abutting edges of a composite wall of a first metallic material, an intermediate layer of a second metallic material, and a third layer of a third metallic material, with one face of the first and third metallic materials in a face-to-face relation with a face of the second metallic material, and with the third metallic material not being directly weldable to the first metallic material,
• (b) a channel formed in an area adjacent the edges of the third layer and the intermediate layer, and further extending into the intermediate layer underlying the third layer,
• (c) a groove formed in the first metallic material at the abutting edges,
• (d) a weld in said groove joining the first material material, said first metallic material being of uniform thickness on opposing sides of said weld under said channel and beneath edges of said intermediate and third layers separated by said channel,
• (e) separate backup strip means of the third metallic material spaced laterally from each other and located at the respective sides of said channel overlying said first metallic material, and partially underlying the third layer in the channel formed in the intermediate layer, said backup strip means having a thickness substantially equal to thickness of said intermediate layer and having opposed edges laterally spaced from each other by a distance which is less than that separating said edges of said third layer,
• (f) an inlay strip of the third metallic material with edges positioned on said backup strip means, bridging said channel and abutting the edges of the layer of third metallic material in said channel, said inlay strips having a longitudinally extending convolution for acommodating lateral thermal expansion, and
• (g) welds joining the abutting edges of the inlay strip and said layer of third metallic material to the backup strip means of third metallic material.