All,
ISA 75.01 and IEC 60534 use the "specific heat ratio" for control valve sizing. Does this "specific heat ratio" mean the ideal gas specific heat ratio (evaluated by k = Cp (Cp-R) ) or does it mean the actual isentropic exponent (same isentropic exponent used in orifice sizing and relief...
We have an air cooled propane condenser. The condenser is located at the high point in the discharge piping of the compressor. The inlet and outlet piping to/from the condenser are from the bottom. Short of CFD analysis, is anyone aware of calculations that can be done to confirm if...
We had a pilot PRV stick full open for about 12 hours. When the PRV was taken offline fore repairs it was noticed that the PRV soft seat had partially melted along the outside edge. The melting temperature of the soft seat is > 160 deg C, however, the measured gas temperature during the...
Asme B31.3 allow use of carbon steel and low temperatures based on stress ratio. However, my reading of Asme B31.3 is that for low temperature carbon steel grade material (LTCS) that is already impacted tested at -46 C, it CAN NOT be used at lower than -48 C if the stress ratio is above 0.3...
We experienced a catastrophic failure of a brazed aluminum heat exchanger (blowout of cover). The vendor report on the failure cites the reason for the failure as due to frequent (approx 100) excursions in temperature where temperature difference between the warm stream and cold stream...
Does the HTRI Xace program for air coolers take into account the assumed ambient wind speed when running a natural draft cooling case? The link below indicates that the ambient wind speed can have a significant impact on the cooling duty for natural draft. I have looked through the HTRI Xace...
We have an MDEA absorber to remove CO2/H2S in a natural gas stream. The MDEA co-absorbs a small amount of hydrocarbons in the absorber that is mostly flashed off from the rich solvent in the flash column. The normal flash gas from the flash column is, say, 1000 Nm3/h, based on a natural gas...
Refer to attached schematic.
The scenario: We have an acid gas removal unit which uses a liquid solvent to treat natural gas. There are three columns (absorber COL-1, flash column COL-2, regenerator COL-3). Absorber COL-1 operates at around 70 barg. For the case where the solvent flow to...
Refer to attached drawing.
We have two 2" ball valves that tie into a cryogenic line (minus 100 C). The ball valves have cavity vents. In between the ball valves is a check valve. There is a small section (6" long) of piping at the end of "Valve 2", followed by a blind flange. The...
Our API 674 positive displacement reciprocating pump has a suction pressure of ~ 2 barg and discharge pressure of ~140 barg. The vendor is proposing a 150# flange for the suction and 1500# for the discharge. Is this acceptable/normal? The concern is that if the pump is isolated (suction...
We have safety relief valves which can relieve large amounts (1000 m3/hr) of cryogenic liquids (-150 degC) to a 150# flare header (48"). The flare header is sized for other gas relief cases. Is it normal practice to design the flare header supports to take into account potential thermal...
We have a shell and tube exchanger which has gas on the shell side and liquid on the tube side. On the gas side, the exchanger has one inlet nozzle on the top side and two outlet nozzles. One gas outlet nozzle (say Nozzle A) is at the bottom while the other gas outlet nozzle (say Nozzle B) is...
We have a boiler generating steam to users (heat exchangers). Our steam system design if as follows:
1) Two PSVs on boiler steam drum set at 109 barg and 110 barg, respectively. PSVs are designed to ASME boiler code. PSVs are sized for 80% of maximum steam generation capacity of boiler.
2) One...
ASME B31.3 Piping code allows "short term" overpressure subject to the condition that the "in no case shall the increased pressure exceed the test pressure", refer section 302-2.4 (e) of B31.3. The question is if a piping system which contains category D fluid has been subject to a Service...
I have noticed on several designs where a PRV is installed in a main line with cold insulation (on the main line), the insulation is only applied on a short section of the PRV inlet line branch. The remainder of the branch line to the PRV is not insulated. Can someone explain why no cold...
A steam desuperheater on our project is designed to B31.1 piping code. B31.1 allows a short term overpressure up to 20%. However, according to the vendor of the desuperheater the B31.3 short term overpressure allowance of up to 33% can be utilized, even though the desuperheater is designed to...
