Good Morning to all.

When we define two seperate vectors for PSV forces, what kind of cases are to be prepared for OPE/STNDBY Conditions?

Type 1

W HGR
W+T1+P1 HGR
WW+HP+H HYD
W+T1+P1+H OPE (Operating Line Temp/ Both at OPE)
W+T2+P2+H OPE (Design Temp/Both at Design)
W+T3+P3+H OPE (Operating PSV1 & STNDBY PSV2 at OPE Temp)
W+T4+P4+H OPE (Operating PSV2 & STNDBY PSV1 at OPE Temp)
W+T5+P5+H OPE (Operating PSV1 & STNDBY PSV2 at DGN Temp)
W+T6+P6+H OPE (Operating PSV2 & STNDBY PSV1 at DGN Temp)
W+T7+P7+H OPE (Steam Out Temprature/Both at SO Temp)
W+T1+P1+H+WIN1 OPE
W+T1+P1+H+WIN2 OPE
W+T1+P1+H+WIN3 OPE
W+T1+P1+H+WIN4 OPE
W+T2+P2+H+F1 OPE
W+T2+P2+H+F2 OPE
W+P1+H SUS
W+P2+H SUS
W+P3+H SUS
W+P4+H SUS
W+P5+H SUS
W+P6+H SUS
W+P7+H SUS
L11-L4 OCC
L12-L4 OCC
L13-L4 OCC
L14-L4 OCC
L15-L5 OCC
L16-L5 OCC
L24+L17 OCC
L25+L17 OCC
L26+L17 OCC
L27+L17 OCC
L28+L18 OCC
L29+L18 OCC
L4-L17 EXP
L5-L18 EXP
L6-L19 EXP
L7-L20 EXP
L8-L21 EXP
L9-L22 EXP
L10-L23 EXP

Type 2

W HGR
W+T1+P1 HGR
WW+HP+H HYD
W+T1+P1+H OPE (Operating Line Temp/ Both at OPE)
W+T2+P2+H OPE (Design Temp/Both at Design)
W+T3+P3+H OPE (Operating PSV1 & STNDBY PSV2 at OPE Temp)
W+T4+P4+H OPE (Operating PSV2 & STNDBY PSV1 at OPE Temp)
W+T5+P5+H OPE (Operating PSV1 & STNDBY PSV2 at DGN Temp)
W+T6+P6+H OPE (Operating PSV2 & STNDBY PSV1 at DGN Temp)
W+T7+P7+H OPE (Steam Out Temprature/Both at SO Temp)
W+T1+P1+H+WIN1 OPE
W+T1+P1+H+WIN2 OPE
W+T1+P1+H+WIN3 OPE
W+T1+P1+H+WIN4 OPE
W+T5+P5+H+F1 OPE
W+T6+P6+H+F2 OPE
W+P1+H SUS
W+P2+H SUS
W+P3+H SUS
W+P4+H SUS
W+P5+H SUS
W+P6+H SUS
W+P7+H SUS
L11-L4 OCC
L12-L4 OCC
L13-L4 OCC
L14-L4 OCC
L15-L8 OCC
L16-L9 OCC
L24+L17 OCC
L25+L17 OCC
L26+L17 OCC
L27+L17 OCC
L28+L21 OCC
L29+L22 OCC
L4-L17 EXP
L5-L18 EXP
L6-L19 EXP
L7-L20 EXP
L8-L21 EXP
L9-L22 EXP
L10-L23 EXP

I have a confusion on PSV force case (In Bold) that is it to be combined with T2 or with T5/T6 at respective STB/OPE cases.

I am with TYPE 1 cases as we are defining two sepetate force vectors, you need not combine it with T5/T6 as they are same but other PSV is at standby condition.

CORRECT ME IF AM NOT.

Is it something difficult?

or this query is lenghty?

Please somebody.

If PSV1 is on standby, then I would assume this PSV can't fire. So I would think your 2nd set of load cases is more applicable. Of course you could have some project or operating specifications that require additional conditions to be evaluated. These would be your better sources of information.

Thank You Mr. Richard,

I find only PSV Forces, Siesmic Cond. & Wind Cases are to analysed.

What additional Conditions could be?

A little bit late but is interesting to note that these PSV are interlocked, therefore will never be a time when will both operate.

So T1 and T2 are not quite real. I know that still we perform calculation for operating temperature and design temperature as per line list.

And being a closed system, normally you consider POP forces therefore at the time when valve is opening (downstream line cold)

Best regards,