A Summary of 26 Underwater Welding Habitat Jobs
Authors: Gaudiano Anthony V. 
Published: October 2008

ABSTRACT
Underwater, dry environment, habitat welding became an effective tool when it was impractical to raise pipes to the surface for flange attachment or repairs. Summarized are 26 jobs where fusion weld joints were made in an Underwater Welding Habitat. Not being mechanical joints, the possibility of leakage and environmental problems are avoided. The technique was used to join new pipelines, risers, repair and modify existing pipelines, structures, and is applicable to sewer outfall lines, communications cables, etc.

INTRODUCTION
The concept of underwater dry environment habitat welding on pipelines essentially began with the Osborn Patent of 1954, which described an underwater enclosure that was to become the predecessor of welding habitats used today. The patent was ahead of its time and received little attention until shortly before it expired. During the intervening seventeen years, marine pipelines advanced from marshland to open sea in ever-increasing numbers following the first offshore well in 1947, 42 miles south of Morgan City, Louisiana.
The technology of laying marine pipelines kept pace with the increasing water depths, even though pipe diameters increased considerably. However, the technology of joining the large diameter flanged pipe on the sea bottom and the setting of long risers in deep water did not. These remained very time-consuming and difficult tasks. Habitat welding became an effective tool when it was impractical to raise pipes to the surface for flange attachment or repair.
Around 1966, companies that were involved in diving and related activities built various types of underwater welding habitats and made a few repairs on offshore platforms and pipelines, and performed a few hot taps. Because Taylor's largest customer was, and still is, the Marine Pipeline Division of Brown & Root and since diving was also our business, we too began to consider habitat welding.
As the title suggests, this paper discusses 26 underwater dry habitat welding jobs performed principally in the Gulf of Mexico. The sizes included 6 inch nominal to 48 inch outside diameter, joined at depths of 8 feet to 540 feet sea water. Twenty-three jobs were circumferential butt joint type welds in horizontal pipes; 3 were with fillet type welds associated with pipe repairs. Of the total, 12 jobs were performed using an Underwater Welding Habitat (UWH) only, and 14 included the UWH combined with a Submarine Pipe Aligning Rig (SPAR).

EQUIPMENT
Taylor's first Underwater Welding Habitat (UWH-1) was 8' X 8' X 9' high and shaped like a Quonset hut (Figure 1). It carried 9 tons of ballast, had hydraulically operated door seals, and a trunk-tunnel to ensure unobstructed ingress and egress by the diver-welders under any circumstances. It was designed for a maximum of 24" diameter pipe and had rolled plate shims to accommodate pipe sizes down to 6" nominal. The umbilical was connected to the roof of the habitat with a flange.
During the construction of UWH-1, welders who had since become divers practiced welding using the Gas Tungsten Arc Weld (GTAW) process, with emphasis on achieving an inside bead during the root pass.