Editing Piper Alpha (section)

==Piper oilfield==
{{main|Piper oilfield}}
[[File:Piper connections.png|thumb|400x400px|Piper Alpha pipeline connections to shore and neighbouring platforms]]
Four companies ([[Occidental Petroleum|Occidental Petroleum (UK) Ltd]], [[Getty Oil|Getty Oil International (England) Ltd]], [[Allied Corporation#Allied Chemical Corporation|Allied Chemical (Great Britain) Ltd]], and [[Thomson Scottish Associates Ltd]]) formed a joint venture{{efn|name=|At the time of the accident, the four successor companies were respectively [[Occidental Petroleum|Occidental Petroleum (Caledonia) Limited (OPCAL)]] (36.5% of the shares), [[Texaco]] (23.5%), [[Allied Corporation#Allied Chemical Corporation|Union Texas Petroleum]] (20%), and [[Thomson North Sea]] (20%).{{sfnp|Lord Caplan|1997|p=|loc=vol. 1, section 1.2}}}} and obtained an oil-exploration licence in 1972.{{sfnp|Lord Caplan|1997|p=|loc=vol. 1, section 1.2}} They discovered the [[Piper oilfield]] located at {{Coord|58|28|N|0|15|E}} in January 1973,<ref>{{Cite web |title=Piper |url=https://www.og.decc.gov.uk/information/bb_updates/appendices/fields/piper.htm |url-status=dead |archive-url=https://web.archive.org/web/20090825175853/https://www.og.decc.gov.uk/information/bb_updates/appendices/fields/piper.htm |archive-date=25 August 2009 |website=[[Department of Energy and Climate Change]]}}</ref> and began fabrication of the platform, pipelines, and onshore support structures. Oil production started in December 1976, less than four years after discovery (a record rarely beaten ever since),<ref name=":19">{{Cite journal |last1=Macleod |first1=Fiona |last2=Richardson |first2=Stephen |date=June 2018 |title=Piper Alpha – What Have We Learned? |url=https://www.icheme.org/media/1237/lpb261_pg03.pdf |url-status=live |journal=[[Loss Prevention Bulletin]] |issue=261 |pages=3–9 |issn=0260-9576 |archive-url=https://web.archive.org/web/20230906122616/https://www.icheme.org/media/1237/lpb261_pg03.pdf |archive-date=6 September 2023 |access-date=19 December 2023}}</ref> with about {{convert|250000|oilbbl|m3}} of oil per day, later increasing to {{convert|360000|oilbbl|m3}}.<ref name=":18" /> Production declined to {{convert|125000|oilbbl|m3}} by 1988.{{sfnp|Lord Caplan|1997||loc=section 2.2}}

A large, [[fixed platform]], Piper Alpha was located in the Piper oilfield, around {{Convert|120|miles|km|abbr=}} northeast of Aberdeen in {{Convert|474|ft|m|abbr=on}} of water.{{sfnp|Lord Caplan|1997||loc=section 2.3}} Piper Alpha produced [[crude oil]] and [[natural gas]] from 36 [[oil well|wells]].<ref name=":18" /> OPCAL built the [[Flotta oil terminal]] in the [[Orkney Islands]] to receive and process oil from the Piper, [[Claymore oilfield|Claymore]] (both operated by OPCAL), and [[Tartan oil field|Tartan]] ([[Texaco]]) oilfields, each with its own platform.<ref name=":19" /> One {{convert|30|in|cm|adj=on}} diameter main oil [[Submarine pipeline|pipeline]] ran {{convert|128|mi}} from Piper Alpha to Flotta.<ref name=":18" />

The Piper platform was the hub of a network of pipelines connecting it to nearby platforms and to shore. The Tartan field fed oil to Claymore, with the co-mingled oil flowing from Claymore through a short pipeline to join the Piper-Flotta line some {{convert|20|miles}} to the west of Piper.<ref>{{cite web |last=Department of Trade and Industry |author-link=Department of Trade and Industry (United Kingdom) |date=1998 |title=The Energy Report: 25 Years of the Brown Book 1973-1998: Oil and Gas Resources of the United Kingdom. Volume 2. Appendix 11 – Offshore Oil and Gas Trunk and Interfield Pipelines |url=http://www.dbd-data.co.uk/bb1998/append11.htm |url-status=dead |archive-url=https://web.archive.org/web/20161201074452/http://www.dbd-data.co.uk/bb1998/append11.htm |archive-date=1 December 2016 |access-date=3 February 2017 |website=Data by Design }}</ref>

Separate {{convert|18|in|cm|adj=on}} diameter gas pipelines were run from the Tartan platform to Piper, and from Piper to the [[TotalEnergies|Total]]-operated<ref name=":19" /> manifold compression platform MCP-01 some {{convert|30|mi|km}} to the northwest. Another {{Convert|16|in|cm|adj=on}} line connected Claymore to Piper, primarily to provide gas from Piper to the Claymore [[gas lift]] system.<ref name=":18" /> MCP-01 would receive the gas from Piper and Tartan, as well as from the [[Frigg gas field]] (through a separate pipeline), and send the resulting stream to [[St Fergus Gas Terminal]] through a {{Convert|108|miles|km|abbr=out}}, 2 × 32-inch pipeline.{{sfnp|The Hon Lord Cullen|1990|loc=vol. 1, p. 13}}<ref name=":32">{{Cite book |last1=Tønnesen |first1=Harald |title=Frigg Industrial Heritage |last2=Meland |first2=Trude |last3=Hadland |first3=Gunleiv |last4=Steensson |first4=Kathryn |publisher=[[Norwegian Petroleum Museum|Norsk Oljemuseum]] |year=2010 |isbn=978-82-90402-54-4 |editor-last=Gjerde |editor-first=Kristin Øye |location=Stavanger, Norway |pages=151–155 |chapter=The Frigg Area Installations}}</ref>

The inventory of the pipelines was significant, with the main oil line to Flotta containing around 70,000&nbsp;tonnes of oil and the three gas lines linking Piper to the surrounding platforms close to 2,000&nbsp;tonnes of high-pressure gas.<ref name=":26">{{Cite book |last=Sylvester-Evans |first=Rod |title=Forensic Engineering: A Professional Approach to Investigation |publisher=[[Institution of Civil Engineers|Thomas Telford]] |year=1999 |isbn=9780727727879 |editor-last=Neale |editor-first=B.S. |location=London, England |pages=127–137 |chapter=Incident Reconstruction – Piper Alpha Case Study |doi=10.1680/feapati.27879.0013}}</ref> The pressure in the Tartan–Piper and Piper–MCP-01 pipelines was around 127&nbsp;bar.{{sfnp|Spouge|1999|loc=appendix III, p. 5}}