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LIGO Livingston Observatory NewsRecent Whirlwind Of Activity At LIGO Livingston
Livingston Observatory Civil Construction Update
August marked the end of a significantly productive four-month period at LIGO's Livingston site, during which the manufacturing and installation of the Beam Tubes for both the X- and Y-arms was completed, as was the installation of all Vacuum Equipment.
Figure 1 at right exhibits the installation activities at the Livingston site on a typically hectic day.
Even more exciting was the successful pump-down and acceptance test for the X-Arm, an achievement also anticipated for the Y-Arm which is presently undergoing pump-down. On the vacuum side, pump-down and helium-leak testing have begun at the X-Arm End Station.
Progress was swift from May through August with some projects completed ahead of schedule thanks to the exemplary work of both the fabrication and installation crews The early wrap-up came in spite of power system failures and other minor glitches that plagued the site. The frequent electrical problems led our local utility company, DEMCO, to supply the site with a new substation which has virtually eliminated the troublesome power surges.
In early May, the last of 400 tube sections was formed by Chicago Bridge & Iron's (CBI) fabrication crew at its Magnolia Beach factory, shown in Figure 2 at left. The factory was then dismantled. Process Systems International's team completed installation of major Vacuum Equipment, first in the X-Arm End Station by mid-May, and then in the Y-Arm End Station a few weeks later. June saw the completion of Vacuum Equipment installation in the corner station, pictured in Figure 3 at right, and the installation of GNB 44" & 48" Gate Valves on the Y-Arm. Also during June a significant milestone was reached with the completion of CBI site installation of the Beam Tube, with all field welds and helium-leak testing completed. Zero leaks were confirmed, with a project total of 800 tube sections helium-leak tested at the fabrication shops and 808 field girth seams leak-tested in the field, a testament to CBI's welding quality and pre-testing visual inspections.
Towards the end of June direct Global Positioning Satellite (GPS) measurements were taken (through the enclosure) on five of the X-Arm control supports, the results indicating that no re-adjustments were necessary.
By mid-July all Vacuum Equipment had been aligned and installed, and grouting work was set to begin. Towards the end of the month the first accumulation reports came in and the results were most encouraging. CBI completed the second global calibration on the X-Arm on July 30, with monitoring by Residual Gas Analyzers on both modules. The air signature reading on that arm was subsequently accepted. In August CBI began pump-down of the Y-Arm. The rough pumping was completed, the turbo pumps were then connected to the Beam Tube and started. Process System International (PSI) performed electrical and pressure testing in the X-Arm End Station. By mid-month all Vacuum Equipment was installed, aligned and grouted. PSI, meanwhile, was anticipating the start of vacuum system pump-down and helium-leak testing.
In celebration of their hard work and dedication, send-off parties were held for both CBI's Fabrication Crew and their Installation Team--a fitting tribute to their long-time commitment to the LIGO Project's success.
Finally, we were all sorry to see Steve Hand, CBI's Global Positioning Satellite guru, leave CBI for a new job. But LIGO was left in the good hands of Dennis Dickenson and Rich Roche. Both Dickenson and Roche "picked up the ball" superbly, executing a flawless transition, and all the GPS measurements went off without a hitch.
Civil construction of the Livingston Observatory is now substantially concluded. Construction of all buildings, service roads and beam tube enclosures has been successfully completed. The entire site infrastructure--such as fire protection, telephones, water and sanitary system--has been checked out and is now operational. The contractors have demobilized for the most part and only the process of closing out punch list items remains.
One of the challenges of our rural location is the availability of clean and stable electrical power. Initially we found our electrical supply experienced some instabilities. This prevented the proper operation of the air conditioning system and some of the vacuum pumps. As mentioned in Cecil Franklin's article above, the local power company which supplies the observatory, DEMCO, has completed construction of a separate substation dedicated solely for LIGO use. This feature has dramatically improved the quality of electrical power and all electrical systems are now operational. In addition, this improvement significantly reduced power outages due to thunder and lightning storms. Thank you, DEMCO!