70 DESIGN, CONSTRUCTION, AND OUTFITTING 



4. Provided insulation 



5. Enabled the use of radiant heating by embedding several runs of mineral insulated (MI) 

 heating cable in the concrete. Additional heating was installed in the form of household con- 

 vection baseboard and overhead radiant heaters. 



The ventilation system was modeled after a standard submarine system. Atmosphere 

 treatment was determined to be sufficient if lithium hydroxide (LiOH) CO, scrubbers and char- 

 coal filtration were used. The major effort in this regard was to properly channel the supply 

 and return atmosphere to optimize treatment. 



Thus it is seen that the design philosophy involved in the development of Sealab II was very 

 loose and flexible, based on a few supplied parameters and tempered by empirical data, eco- 

 nomics, and time. Since Sealab II was a complex total project, very few design decisions were 

 independent; most affected many other project team members, making this project a good prob- 

 lem in systems engineering. Time and geographic distance precluded lengthy conferences on 

 design decisions. Mostly the decisions were made locally, members of the team informed, and 

 if no objections were heard in a reasonable length of time, production commenced. The results 

 of these philosophies and decisions, the vessel itself and its characteristics, will be discussed 

 in succeeding sections. 



DETAILS OF CONSTRUCTION 



The construction of Sealab II was generally a routine shipyard task with a few interesting 

 exceptions. The production schedule was extremely tight, but not unlike any other more con- 

 ventional shipyard project. Standard shipyard organization and practices were used throughout. 



The ASME Boiler Code under which the main cylinder was constructed provides for cer- 

 tain procedures to be followed in assuring adequate quality. The steel selected for the main 

 structure was 1- in .-thick mild steel, Grade M, of Military Specification MIL 5-16113 and, as 

 such, received extensive testing at the rolling mill. The plate was ultrasonically inspected 

 locally to check for laminations, and other specifications were spot checked. Welding was 

 performed in accordance with current procedures for mild steel (AISI 1015-1025). All welds 

 were radiographed, and films were evaluated according to the latest standards. All welds were 

 defect-free. 



After fabrication of the basic structure, a hydrostatic test to 1-1/2 times working pressure, 

 190 psi, was applied to test for strength. This was done prior to outfitting with fresh water to 

 minimize any harmful effects. After installation of all piping systems and upon completion of 

 all hull penetrations, a tightness test at working pressure was conducted using air. Helium 

 was not used due to economic and time restrictions. 



In general, standard shipyard procedures were used in all phases of construction and test- 

 ing. Quality -control procedures commensurate with those employed on normal shipyard work 

 were invoked. 



As mentioned previously, the schedule was very close and would surely have been missed 

 if it were not for the rapid solution of many production and procurement problems. Fabrica- 

 tion of the large (24 in.) portholes was extremely difficult, since tolerances were very close 

 and hard to maintain in the face of normal welding distortions. Not the least of the procure- 

 ment problems involved the ellipsoidal dished heads used to cap the main cylinder. 



Once design specifications were set, contract bids were let to the normal suppliers of these 

 large dished heads. The production schedule demanded a 30 to 45 day delivery. None of the 

 major steel companies, the normal sources, could begin to touch this time frame. The large 

 size of the heads, coupled with a rash of back orders due to an inpending steel strike, made 

 normal procurement impossible. The earliest delivery that could be expected was five to six 

 months, after the scheduled submergence of Sealab n. 



