SIL Certification For Hydraulic Emergency Shutdown System

SIL = ?

SIL stands for Safety Integrity Level

thanks

Ref IEC 61508/61511 SIL Is applicable to Electical /Electronic programmable safety systems

Regards

Jose

If the system is a "pure hydraulic and pneumatic" emergency shutdown (ie no electrical or electronic (maybe all pilot driven and no solenoids?)) then SIL's would not apply. In which case a Performance Level (PLr) to EN ISO 13849-1 could be applicable HOWEVER this standard is for Machinery not Process Industry hence it might not be so well known or used.

If electrically driven especially from PLC's or computers then SIL standards could still be applicable and the relevant standard should explain how final "mechanical" style devices are to be handled. I don't know the process standards but EN 62061 (SIL's for Machinery) allows you to use EN ISO 13849-1 for such final devices components of a SIL determined system.

hope this helps but I suspect not as the subject matter is involved

Describe the system more completely...I assume hydraulic/ pneumatic operators for the controlled elements, but where do the ESD commands originate, and what inputs cause the ESD ? Also, there are multiple SIL levels... according to your desription, I assume SIL 3 ? Is this application for topsides or subsea ?

Isn't the SIL level determined by following ISA-84 or some other electrical standard? Wouldn't a purely pneumatic/hydraulic system then not meet this by definition? Are you trying to get at what the frequency of failure to act on demand would be for a safety system?

Thanks everybody for useful discussion . In reply to threads 4 & 5 , more elaborate description is as follows .The application is an off-shore O & G platform, where a Hydraulically operated ESD will cause shutdown of SSSV , SSV and ZVs . There are 6 inputs/cause to the ESD i.e Header pressure(high high), Local and remote ESDs, Fire loop alarm etc which cause a shutdown through hydraulic 3 port relays. The ESD will shut down SSV and SSV sequentially through hudraulic pressure in the system. Whole system is fed through a HPU at 3500 Psig.

I personally think SIL level certification shall be applicable bcaz , it Is is more related to determination of Failure on demand rather than medium like electrical or pnenumatic.

It would be useful if some ESD manufacturers representatives join this discussion

Thanks

Functional Safety aims to reduce injury, through three mechanisms. 1) Improved reliability. 2) Failure to Safety (SFF) and 3) Management, Systematic Techniques, Verification and Validation.

The techniques from IEC61508:2010 are focused on reducing mistakes and errors in the electrical/electronics industry.

It is possible to adapt these methods to other applications. For this to be valid, the appropriate technology standards, risks and incidents should be considered.

Any technique that will cost effectively reduce injury should be employed.