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* 18:00: The day shift ended, and the night shift started with 62 men running Piper Alpha. As he found the on-duty custodian busy, the engineer neglected to inform him of the condition of Pump A. Instead he placed the permit in the control centre and left. This permit disappeared and was not found. Coincidentally there was another permit issued for the general overhaul of Pump A that had not yet begun.
*19:00: Fire-fighting system put under manual control: Like many other offshore platforms, Piper Alpha had an [[automatic fire suppression|automatic fire-fighting system]], driven by both diesel and electric pumps (the latter were disabled by the initial explosions). The diesel pumps were designed to suck in large amounts of sea water for fire fighting; the pumps had automatic controls to start them in case of fire (although they could not be remotely started from the control room in an emergency).{{fix|link=Wikipedia:citation needed|date=July 2019|text=Why not?}} However, the fire-fighting system was under manual control on the evening of 6 July: the Piper Alpha procedure adopted by the [[Offshore installation manager|Offshore Installation Manager]] (OIM) required manual control of the pumps whenever divers were in the water (as they were for approximately 12 hours a day during summer) although in reality, the risk was not seen as significant for divers unless a diver was closer than {{convert|10–15|ft|m|0}} from any of the four {{convert|120|ft|m|-1}} level caged intakes. A recommendation from an earlier audit had suggested that a procedure be developed to keep the pumps in automatic mode if divers were not working in the vicinity of the intakes as was the practice on the Claymore platform, but this was never implemented.<ref>The Case for Safety: The North Sea Piper Alpha Disaster; NASA Safety Center, System Failure Case Study, May 2013 Volume 7 Issue 4, p3.</ref>
*21:45: Pump B tripped and could not be restarted: Because of problems with the methanol system earlier in the day, [[methane clathrate]] (a flammable ice) had started to accumulate in the gas compression system pipework, causing a blockage. Due to this blockage, condensate (natural gas liquids NGL) Pump B stopped and could not be restarted. As the entire power supply of the offshore construction work depended on this pump, the manager had only a few minutes to bring the pump back online, otherwise the power supply would fail completely. A search was made through the documents to determine whether Condensate Pump A could be started.
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