The Effect of Reduced Design Margin on the Fire Survivability of ASME Code Propane Tanks

2004 ◽  
Author(s):  
A. M. Birk
Keyword(s):  
Pressure Vessels ◽  
Relief Valve ◽  
Pressure Relief ◽  
Mode Of Failure ◽  
Asme Code ◽  
Failure Scenario ◽  
Fill Level ◽  
Relief System ◽  
And Storage ◽  
Design Margin

The design margin on certain unfired pressure vessels has recently been reduced from 4.5 to 4.0 to 3.5. This has resulted in the manufacture of propane and LPG tanks with thinner walls. For example, some 500 gallon ASME code propane tanks have had the wall thickness reduced from 7.7 mm in 2001 to 7.1 mm in 2002 and now to 6.5 mm in 2004. This change significantly affects the fire survivability of these tanks. This paper presents both experimental and computational results that show the effect of this design change on tank fire survivability to fire impingement. The results show that for the same pressure relief valve setting, the thinner wall tanks are more likely to fail in a given fire situation. In severe fires, the thinner walled tanks will fail earlier. An earlier failure usually means the tank will fail with a higher fill level, because the pressure relief system has had less time to vent material from the tank. A higher liquid fill level at failure also means more energy is in the tank and this means the failure will be more violent. The worst failure scenario is known as a boiling liquid expanding vapour explosion (BLEVE) and this mode of failure is also more likely with the thinner walled tanks. The results of this work suggest that certain applications of pressure vessels such as propane transport and storage may require higher design margins than required by the ASME.

The Effect of Reduced Design Margin on the Fire Survivability of ASME Code Propane Tanks

2005 ◽  
Vol 127 (1) ◽  
pp. 55-60
Author(s):  
A. M. Birk
Keyword(s):  
Wall Thickness ◽  
Pressure Vessels ◽  
Relief Valve ◽  
Pressure Relief ◽  
Asme Code ◽  
Section Viii ◽  
Failure Scenario ◽  
Fill Level ◽  
Relief System ◽  
Design Margin

In the 1999 addenda to the 1998 ASME pressure vessel code, Section VIII, Div. 1 there was a change in design margin for unfired pressure vessels from 4.0 to 3.5. This has resulted in the manufacture of propane and LPG tanks with thinner walls. For example, the author has purchased some new 500 gallon ASME code propane tanks for testing purposes. These tanks had the wall thickness reduced from 7.7 mm in 2000 to 7.1 mm in 2002 and now to 6.5 mm in 2004. These changes were partly due to the code change and partly due to other factors such as steel plate availability. In any case, the changes in wall thickness significantly affects the fire survivability of these tanks. This paper presents both experimental and computational results that show the effect of wall thickness on tank survivability to fire impingement. The results show that for the same dank diameter, tank material, and pressure relief valve setting, the thinner wall tanks are more likely to fail in a given fire situation. In severe fires, the thinner walled tanks will fail earlier. An earlier failure usually means the tank will fail with a higher fill level, because the pressure relief system has had less time to vent material from the tank. A higher liquid fill level at failure also means more energy is in the tank and this means the failure will be more violent. The worst failure scenario is known as a boiling liquid expanding vapor explosion and this mode of failure is also more likely with the thinner walled tanks. The results of this work suggest that certain applications of pressure vessels such as propane transport and storage may require higher design margins than required by Section VIII ASME code.

The Effect of Pressure Relief Valve Blowdown and Fire Conditions on the Thermo-Hydraulics Within a Pressure Vessel

2006 ◽  
Vol 128 (3) ◽  
pp. 467-475 ◽  
Author(s):  
A. M. Birk ◽  
J. D. J. VanderSteen
Keyword(s):  
Thermal Stratification ◽  
Pressure Vessels ◽  
Pressure Relief Valve ◽  
Relief Valve ◽  
Pressure Relief ◽  
Pressure Transducers ◽  
Hydrocarbon Pool ◽  
Computer Controlled ◽  
C 50 ◽  
Fire Conditions

In the summers of 2000 and 2001, a series of controlled fire tests were conducted on horizontal 1890liter (500 US gallon) propane pressure vessels. The test vessels were instrumented with pressure transducers, liquid space, vapor space, and wall thermocouples, and an instrumented flow nozzle in place of a pressure relief valve (PRV). A computer controlled PRV was used to control pressure. The vessels were heated using high momentum, liquid propane utility torches. Open pool fires were not used for the testing because they are strongly affected by wind. These wind effects make it almost impossible to have repeatable test conditions. The fire conditions used were calibrated to give heat inputs similar to a luminous hydrocarbon pool fire with an effective blackbody temperature in the range of 850°C±50°C. PRV blowdown (i.e., blowdown=poppressure−reclosepressure) and fire conditions were varied in this test series while all other input parameters were held constant. The fire conditions were varied by changing the number of burners applied to the vessel wall areas wetted by liquid and vapor. It was found that the vessel content’s response and energy storage varied according to the fire conditions and the PRV operation. The location and quantity of the burners affected the thermal stratification within the liquid, and the liquid swelling (due to vapor generation in the liquid) at the liquid∕vapor interface. The blowdown of the PRV affected the average vessel pressure, average liquid temperature, and time to temperature destratification in the liquid. Large blowdown also delayed thermal rupture.

Study on the Relief Capacity and Safety Integrity of Multiple Relief Valves of Charge Gas Pipe in Ethylene-Cracking Plant

2013 ◽  
Author(s):  
Jianxin Zhu ◽  
Xuedong Chen ◽  
YunRong Lu ◽  
Zhibin Ai ◽  
Weihe Guan
Keyword(s):  
Large Scale ◽  
Relief Valve ◽  
Pressure Relief ◽  
Emergency Relief ◽  
Safety Integrity Level ◽  
Upstream Pressure ◽  
Minimum Number ◽  
The Difference ◽  
Relief System

The shutdown of charge gas compressor in large-scale ethylene-cracking plant always involves emergency pressure relief of charge gas through multiple safety valves. The emergency relief capacity plays an important role on the safety of the overall plant. In this paper, by studying the difference between the configuration of the pressure relief system of two 1000 KTA ethylene-cracking plants (the inner diameters of the charge gas pipeline in both plants are 2m, while the number of same-sized relief valves are 28 and 19, respectively), the relief capacity of multiple relief valves is studied and compared with empirical calculation and numerical analysis. It is found that, due to the interruption of fluid flow when compressor is emergency shutdown, the upstream pressure of each relief valve increase steadily with the continuously make-up of the charge gas, but the difference between the inlet pressure of all relief valves can be neglected. With the increase of the upstream pressure, the opening of relief valves is determined mainly by the set pressure. In multiple valves pressure relief scenario, normally the downstream valves have greater relief capacity than those upstream valves if both relief valves have the same back pressure. Also, by analysis it is noted that the pressure relief capacities of multiple relief valves in both plants are sufficient. The minimum number of relief valves required for process safety is obtained. The maximum achievable Safety Integrity Level (SIL) of pressure relief system is determined by calculation of the reliability of the redundant relief valves. The analysis is used for determination of the SIL of the pressure relief system. The finding is also significant for determination of the required capacity of multiple relief valves.

On the Transition From Non-BLEVE to BLEVE Failure for a 1.8M3 Propane Tank

2006 ◽  
Vol 128 (4) ◽  
pp. 648-655 ◽  
Author(s):  
A. M. Birk ◽  
J. D. J. VanderSteen
Keyword(s):  
Pressure Vessels ◽  
Total Loss ◽  
Relief Valve ◽  
Initial Rupture ◽  
Asme Code ◽  
The Difference ◽  
Heated Length ◽  
Insight Into ◽  
Vapor Space ◽  
Fire Conditions

A series of fire tests were conducted on nine, 1.8m3(500USgal) ASME code propane pressure vessels to study the significance of pressure relief valve behavior on tank survivability to fire impingement. In these tests three tanks ruptured (i.e., finite failure) and six boiling liquid expanding vapor explosion (BLEVEd) (total loss of containment). The difference between the BLEVE and non-BLEVE failures was due to a difference in the fire conditions. It is believed that these tests show some insight into the BLEVE process. In all tests the fire consisted of an array of nominal 590kW(2MBTU∕h) liquid propane burners. A pool fire was not used because of the uncontrolled nature of open pool fires. It was believed that very repeatable fire conditions could be achieved by using a series of burners. In the tests where the outcome was a non-BLEVE there were two burners mounted 30cm above the tank on the tank vapor space. These burners were used to weaken the steel and to initiate a failure. To heat the liquid, there were between 4 and 12 burners applied below the liquid level. When one burner was added on the vapor space, all of the remaining tanks BLEVEd. This was true over a range of fill levels (at failure) of between 10% and 50% by volume. It is believed this added burner was just enough to weaken the tank so that any initial rupture would grow towards a total loss of containment and BLEVE. This paper presents the details of this test series and shows how severely heated length and liquid energy affected the outcome.

Laboratory Testing of Safety Relief Valves

2017 ◽  
Author(s):  
Thomas Kegel ◽  
William Johansen
Keyword(s):  
Design Element ◽  
Property A ◽  
Relief Valve ◽  
Pressure Relief ◽  
Excessive Pressure ◽  
Component Failure ◽  
Fluid Handling ◽  
Personnel Safety ◽  
And Storage ◽  
System Volume

Industrial fluid handling and storage systems can experience excessive pressure resulting from process upsets. A catastrophic component failure can compromise personnel safety or damage property. A pressure relief valve (PRV) represents a common design element that allows material to be vented to reduce pressure and restore safe conditions. Obviously selecting the proper PRV requires specification of the relief pressure. Less obvious might be the requirement of confirming that the flowrate is adequate to vent the system volume. Paper published with permission.

Background and Summary of Revisions to Appendix M of ASME Section VIII, Division 1: Stop Valves Located in the Pressure Relief Path

2004 ◽  
Author(s):  
Richard J. Basile ◽  
Clay D. Rodery
Keyword(s):  
Pressure Vessel ◽  
White Paper ◽  
Pressure Vessels ◽  
Relief Valve ◽  
Pressure Relief ◽  
Stop Valve ◽  
Division 1 ◽  
Section Viii ◽  
Current Code ◽  
Petrochemical Industries

Appendix M of Section VIII, Division 1 of the ASME Boiler and Pressure Vessel Code[1] provides rules for the use of isolation (stop) valves between ASME Section VIII Division 1 pressure vessels and their protective pressure relieving device(s). These current rules limit stop valve applications to those that isolate the pressure relief valve for inspection and repair purposes only [M-5(a), M-6], and those systems in which the pressure originates exclusively from an outside source [M-5(b)]. The successful experience of the refining and petrochemical industries in the application and management of full area stop valves between pressure vessels and pressure relief devices suggested that the time was appropriate to review and consider updates to the current Code rules. Such updates would expand the scope of stop valve usage, along with appropriate safeguards to ensure that all pressure vessels are provided with overpressure protection while in operation. This white paper provides a summary of the current Code rules, describes the current practices of the refining and petrochemical industries, and provides an explanation and the technical bases for the Code revisions.

Relief Tanks: Parameters to Consider When Designing Relief Systems and Connections to Tanks

2020 ◽  
Author(s):  
Emma Perez
Keyword(s):  
Cold Weather ◽  
Transient Pressure ◽  
Relief Valve ◽  
Cold Temperatures ◽  
Oil Storage ◽  
Effects Of Temperature ◽  
Relief System ◽  
And Storage ◽  
Proper Operation ◽  
Stagnant Fluid

Abstract Oil Storage facilities (terminals) are usually designed with a pressure rating lower than the rating of the pipeline transporting the fluids. During abnormal operations, terminal piping can be subject to unexpected transient pressure surges that can exceed the allowed values. Mitigations are required a common one is installing a relief system. When a relief valve is installed, it is connected to a tank and the location of this relief tank is critical for the proper operation of the relief system and the overall mitigation of pressure surges. Relief design needs to take into account the length and layout of the piping. Facilities in the northern hemisphere contain pipes installed above ground and prone to experiencing cold temperatures during winter months. If the fluid is stagnant in these pipes, the cold weather increases the viscosity of the fluid. If the relief valve activates, the fluid that has been stagnant in the pipe needs to be pushed out of the pipe and into the tank. This requires a high pressure from the system and is directly affected by the distance of the pipe and the properties of the stagnant fluid. This paper will show how transient pressures change for length of pipe and for varied viscosities of the stagnant fluid. With these findings, engineers can improve their understanding of the effects of temperature and length on surge pressures and they can design safer systems for liquid transportation and storage.

Power Actuated Pressure Relief Valve for High Pressure Vessels

2003 ◽  
Author(s):  
Anders C. Tra¨ff ◽  
Peter C. Jansson
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Pressure Vessels ◽  
Attractive Alternative ◽  
Powder Materials ◽  
Relief Valve ◽  
Pressure Relief ◽  
Pressure Medium ◽  
Pressure Relief Valves ◽  
Very High

The pressure required for treatment of food ranges from 300 to 600 MPa, depending on the food being processed and the desired results, higher pressure giving better and more economical results. However, there are currently no predictable, reliable, and repeatable safety devices available for very high pressures like 600 MPa. Rupture disks have a short life at these pressures, and pressure relief valves for very high pressure are not repeatable. Thus the possibility of using a system design is an attractive alternative that will make the overpressure protection more reliable and controllable. In current applications, high-pressure vessels normally operate from a few MPa to 200 MPa, for example when extracting substances, compacting powder materials, or healing defects in materials. The pressure medium is typically a pure gas or a liquid. Here existing devises serve their purpose. The request for mild treatment of food to enhance safety and quality has created a niche for very high pressure. With this new technique the food is treated at low temperature and high pressure for a short time. The treatment inactivates micro organisms but maintains the nutritional and organoleptic values of the food, achieving a food with high quality and increased safety throughout its commercial shelf life.

Air Tests of Commercially Available Transport Vessel PRVs

1999 ◽  
Vol 122 (2) ◽  
pp. 204-209
Author(s):  
A. J. Pierorazio ◽  
A. M. Birk
Keyword(s):  
Energy Storage ◽  
Test Bench ◽  
Initial Step ◽  
Third Party ◽  
Operating Characteristics ◽  
Relief Valve ◽  
Pressure Relief ◽  
Vapor Explosions ◽  
Transport Vessel ◽  
And Storage

An experimental study of boiling liquid expanding vapor explosions (BLEVE) was recently completed at Queen’s University in Canada. The results clearly showed that the severity of the BLEVE was directly related to the energy stored in the vessel, and this energy storage was significantly affected by pressure relief valve (PRV) behavior. During the tests, the PRV operating characteristics were highly variable. Since these valves play a large role in the control of energy accumulation and storage in a pressure vessel, it was decided to study their dynamic behavior in detail and quantify their effect on energy storage. As an initial step, 60 small (1-in. NPT) transport vessel PRVs representing equivalent designs from each of three manufacturers were procured through a third party and tested on an air test bench. These tests were conducted in accordance with the certification procedures specified by various agencies (ASME, UL, CSA, CGA). Four characteristic pressures were measured: simmer (start-to-discharge), pop (full open), reseat, and reseal (bubble-tight reclosure). After initial testing, the valves were stored for various periods of time and retested. This paper details the equipment, procedures, and results of this testing and contains a significant discussion about the expected and observed operation of relief valves. [S0094-9930(00)00702-2]

Thermal Protection of Pressure Vessels by Internal Wall Cooling During Pressure Relief

1990 ◽  
Vol 112 (4) ◽  
pp. 427-431 ◽  
Author(s):  
A. M. Birk
Keyword(s):  
Thermal Protection ◽  
Internal Surface ◽  
Spray Cooling ◽  
Pressure Vessels ◽  
Material Degradation ◽  
Relief Valve ◽  
Pressure Relief ◽  
Thermal Barriers ◽  
Ultimate Failure ◽  
External Water

When pressure vessels are exposed to external fire impingement, high wall temperatures can result and these can lead to material degradation and the ultimate failure of the vessel. To protect against this possibility, vessels can be protected by means of pressure relief devices, external thermal barriers or external water spray cooling. This paper deals with a device that cools the walls of fire-impinged vessels carrying pressurized liquids by directing 2-phase fluid along the upper internal surface of the vessel when the vessel pressure relief valve is in action. The device consists of a concentric secondary internal shell that partitions the interior into a core region and an annulus. The bottom of the internal shell is open to allow communication between the two regions. When vapor is vented from the annulus, it results in significant fluid swelling in the annular space. This swelling results in large areas of the wall being wetted and cooled by liquid. Experimental results are presented for the case of a short electrically heated cylindrical vessel with and without the cooling device installed. From the limited tests conducted, it was shown that the device cools areas of the vessel wall that would normally have experienced high wall temperatures and possible material degradation.

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