10492 STFC Liquid H2 Cooling System HAZOP Actions Action responses for Mark Tucker HAZOP ACTION RESPONSE FORM client STFC project STFC MICE Liquid Hydrogen Cooling System HAZOP project no 10492 master drawing number TD-1085-100-01: Baseline P&ID MICE Hydrogen System Rev L Node 1 Case 3 H2 operation mode: Hydrogen Side Purge Priority 1 Must be resolved/completed before system is operated Guide word / Parameter None / Loss of... Flow Deviation Hand valve closed on pressure relief lines (ie. HV61 / HV41 / HV47). Consequence Loss of overpressure protection as the relief path has been isolated. Existing Safeguards - Operator Intervention None identified. Independent safeguards None identified. Recommendation 1. Review whether hand valves on all relief lines should be removed or locked open. 2. Consider fitting a regulator on cylinder pack to limit high pressure to the system in case of regulator failure. The system could see up to 220 barg and although the system pipework is designed for this pressure, the relief valves are not. Comment This event has been reviewed in a previous LOPA study. Responsibility Mark Tucker - [email protected]Required Response Date 2017-05-24 Response Date : 2017-05-19 Response Signature :
Transcript
10492 STFC Liquid H2 Cooling System HAZOP Actions
Action responses for Mark Tucker
HAZOP ACTION RESPONSE FORM
client STFCproject STFC MICE Liquid Hydrogen Cooling System HAZOP
project no 10492master drawing number TD-1085-100-01: Baseline P&ID MICE Hydrogen System Rev L
Node 1 Case 3 H2 operation mode: Hydrogen Side PurgePriority 1 Must be resolved/completed before system is operated
Guide word / Parameter None / Loss of... FlowDeviation Hand valve closed on pressure relief lines (ie. HV61 / HV41 / HV47).
Consequence Loss of overpressure protection as the relief path has been isolated.Existing Safeguards -
Operator Intervention None identified.
Independent safeguards None identified.
Recommendation
1. Review whether hand valves on all relief lines should be removed or locked open.
2. Consider fitting a regulator on cylinder pack to limit high pressure to the system in case of regulator failure. The system could see up to 220 barg and although the system pipework is designed for this pressure, the relief valves are not.
Comment This event has been reviewed in a previous LOPA study.Responsibility Mark Tucker - [email protected]
Required Response Date 2017-05-24Response Date : 2017-05-19
Response Signature :Final Action / Review
Team Comment :
Date Response Accepted :Acceptor's Signature
(HAZOP Chair or Secretary):
We think that the hand valves concerned should be HV61, HV46 and HV49 in the bottle cage
RESPONSE: The hand valve HV46 to the relief valve RV51 has a lockable cap (currently only for the closed position). We will obtain a lockable cap for the open position. This relief valve RV51, which passes at 10 psi, ensures that the system does
10492 STFC Liquid H2 Cooling System HAZOP Actions
not see a high pressure in the case of regulator failure or incorrect settings. The hand valves HV49 and HV61 to the relief valves RV62 and RV50 will be fitted with locking mechanisms to keep them in the closed position and prevent unauthorized operation. It is not necessary to fit a regulator directly on to the bottle pack as the pipework and fittings here are suitable for the pack pressure of up to 4000psi.
In essence: HV46 will always be in a state ‘locked-open’ to allow a path to RV51. RV51 is the only over-pressure protection in the gas bottle cage.
10492 STFC Liquid H2 Cooling System HAZOP Actions
10492 STFC Liquid H2 Cooling System HAZOP Actions
HAZOP ACTION RESPONSE FORM
client STFCproject STFC MICE Liquid Hydrogen Cooling System HAZOP
project no 10492master drawing number TD-1085-100-01: Baseline P&ID MICE Hydrogen System Rev L
Node 1 Case 5 H2 operation mode: Hydrogen Side PurgePriority 1 Must be resolved/completed before system is operated
Guide word / Parameter More / Excess of... PressureDeviation Failure of pressure regulator PR36
Consequence Potential for downstream equipment to see high pressure leading to equipment damage.
Independent safeguards Downstream pressure regulator HA-PR38 limits pressure to main system. There is a pressure relief valve and bursting disc on the same line.
Recommendation Clarify whether the bursting disc BD57 exists and consider whether this is required as there is an existing relief valve on the line.
Comment This event has been reviewed in a previous LOPA study.Responsibility Mark Tucker - [email protected]
Required Response Date 2017-05-24Response Date : 2017-05-19
Response Signature :Final Action / Review
Team Comment :
Date Response Accepted :Acceptor's Signature
(HAZOP Chair or Secretary):
RESPONSE: The bursting disc BD57 does not exist, is not necessary, and will be removed from the P&ID drawing. The line is protected from over-pressure by relief valve RV56.
Equally, BD55 does not exist, will be removed from the P&ID and line is protected by RV53
10492 STFC Liquid H2 Cooling System HAZOP Actions
10492 STFC Liquid H2 Cooling System HAZOP Actions
HAZOP ACTION RESPONSE FORM
client STFCproject STFC MICE Liquid Hydrogen Cooling System HAZOP
project no 10492master drawing number TD-1085-100-01: Baseline P&ID MICE Hydrogen System Rev L
Node 1 Case 8 H2 operation mode: Hydrogen Side PurgePriority 1 Must be resolved/completed before system is operated
Guide word / Parameter Less... PressureDeviation Low supply pressure from helium cylinder.
Consequence Inefficient purge of the system resulting in process inefficiency as additional purges will be required.
Existing Safeguards - Operator Intervention
Operator routinely checks pressure of the cylinders to ensure that the cylinder pressure is suitable for operation.
Independent safeguards The system monitors pressure during the purge sequence.
RecommendationReview whether gas quantity provided by existing cylinders is sufficient for the required operation and whether a helium pack containing more cylinders should be used.
Responsibility Mark Tucker - [email protected] Response Date 2017-05-24
Response Date : 2017-05-19Response Signature :
Final Action / Review Team Comment :
Date Response Accepted :Acceptor's Signature
(HAZOP Chair or Secretary):
RESPONSE: The regulator for the purge helium gas supply has a switchable dual input so that two cylinders or packs are attached before beginning the gas processes. Purging of the buffer and absorber requires 1200 bar litres per flush. The purge sequence consists of three evacuation and flush cycles. Hence, including the purge of the supply lines, around 4000 bar litres is required. This is equivalent to less than half of one helium gas cylinder initially at 220 bar. Therefore, the attachment of two full gas cylinders gives an ample reservoir
10492 STFC Liquid H2 Cooling System HAZOP Actions
of helium gas for the purging and helium fill sequences because it is not possible to liquefy the helium gas.
The requirement for two full helium gas cylinders being connected before the purge sequence will be included in the operating instructions.
10492 STFC Liquid H2 Cooling System HAZOP Actions
HAZOP ACTION RESPONSE FORM
client STFCproject STFC MICE Liquid Hydrogen Cooling System HAZOP
project no 10492master drawing number TD-1085-100-01: Baseline P&ID MICE Hydrogen System Rev L
Node 1 Case 10 H2 operation mode: Hydrogen Side PurgePriority 1 Must be resolved/completed before system is operated
Guide word / Parameter Other Than... FlowDeviation Valve HA-PV17 passing
Consequence Potential for air ingress into system as this line is connected to an open vent. Potential for inefficient purge.
Existing Safeguards - Operator Intervention
Operator will see loss of vacuum in the system during this stage and identify an issue.
Independent safeguards None identified.
Recommendation Review whether a non-return valve is required between Valve HA-PV17 and the nitrogen line to protect against reverse flow.
Responsibility Mark Tucker - [email protected] Response Date 2017-05-24
Response Date : 2017-05-19Response Signature :
Final Action / Review Team Comment :
Date Response Accepted :Acceptor's Signature
(HAZOP Chair or Secretary):
RESPONSE: There has been no evidence yet of valve PV17 passing gas when closed. This is tested during pressure-rise tests, when the pipework is evacuated and isolated, before each operational cycle of filling and cooling. The pipework is purged with helium gas at least three times before hydrogen is allowed to enter, or cooling is begun, so there is very little likelihood of significant amounts of nitrogen being pulled in from the vent line and remaining in this pipework after the purging sequence. Thereafter, during the cooling process, the pipework is maintained above the pressure in the nitrogen line and this will impede reverse flow.
10492 STFC Liquid H2 Cooling System HAZOP Actions
(It would be possible to install a non-return valve between valve PV17 and the nitrogen line. This check valve would need to allow forward flow at low pressures above 1 – 3 psi gauge to be useful. However, check valves of this rating normally require a back pressure of several psi to ensure closure, for example Swagelok series C, which would not guarantee protection against PV-17 passing gas).
In essence: thorough leak-checking is the safeguard against leaks.
Indication of the location and potential size of a reverse-flow valve.
Need to cut this 1” diameter pipe and insert the check valve here.
ee
10492 STFC Liquid H2 Cooling System HAZOP Actions
HAZOP ACTION RESPONSE FORM
client STFCproject STFC MICE Liquid Hydrogen Cooling System HAZOP
project no 10492master drawing number TD-1085-100-01: Baseline P&ID MICE Hydrogen System Rev L
Node 2 Case 2 H2 operation mode: Hydrogen Side Purge (H2 supply Line)Priority 1 Must be resolved/completed before system is operated
Guide word / Parameter Other than... FlowDeviation Valves HV47, HV52 and HV54 passing.
ConsequencePotential for release of helium to local area leading to an asphyxiant atmosphere or air ingress during vacuum stage leading to inefficient purge.
Recommendation Review whether valves HV47, HV52 and HV54 should be blanked off or plugged.
Responsibility Mark Tucker - [email protected] Response Date 2017-05-24
Response Date : 2017-05-19Response Signature :
Final Action / Review Team Comment :
Date Response Accepted :Acceptor's Signature
(HAZOP Chair or Secretary):
RESPONSE: The hand valve HV47 on the regulator panel in the hydrogen bottle cage is blanked off on the ‘atmosphere side’ with a VCR plug. The hand valves HV52, on the nitrogen regulator panel, and HV54, on the helium purge regulator panel, have been blanked off on their ‘atmosphere sides’ with Swagelok compression fitting caps. Blanking caps will be included in the P&ID together with the key list on that sheet.
10492 STFC Liquid H2 Cooling System HAZOP Actions
10492 STFC Liquid H2 Cooling System HAZOP Actions
And
Compression fitting caps visible next to HV54 and HV52
