[SystemSafety] LOPA

[W.L. Mostia]

It is fairly common industry practice to have two slide gate valves for this service.


William (Bill) L. Mostia, Jr PE
ISA Life Fellow, TUV FS Engineer
Principle Engineer
WLM Engineering Co.

281-728-3722

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From: paul_e.bennett at topmail.co.uk<mailto:paul_e.bennett at topmail.co.uk>
Sent: Monday, February 15, 2021 2:50 PM
To: systemsafety at lists.techfak.uni-bielefeld.de<mailto:systemsafety at lists.techfak.uni-bielefeld.de>
Subject: [SystemSafety] LOPA

While the rest of you are being so quiet, I thought I would drop a
link to the video I saw recently. I know it is about a year old and the
event was more than two years ago, but I figured it would be of
interest here.

<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D3RFDKpwdbEA&data=04%7C01%7C%7C2548d2b27fca4bf338cc08d8d1f35ce1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637490190458339389%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=aDRsPPyqhaArwYT7I7b1DtfFGODY5xnX3VMevmMFN4w%3D&reserved=0>

It seems that the catalyst  only had a single means of stopping its flow,
and its being eroded reduced its effectiveness. One might wonder why
a second slide valve in series, only used for shutdowns, was not thought
to be a useful protection measure that might have prevented the disaster.

How many think of doing a LOPA for the software they write? The adding
of definitive protective containments.

Regards

Paul E. Bennett IEng MIET
Systems Engineer
Lunar Mission One Ambassador
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