LPG Safety Distance Guide

PETRONAS TECHNICAL STANDARDS DESIGN AND ENGINEERING PRACTICE

MANUAL

GUIDELINE FOR CALCULATING SAFETY DISTANCES IN LPG STORAGE AND HANDLING INSTALLATIONS

PTS 20.162 JANUARY 1988

PREFACE

PETRONAS Technical Standards (PTS) publications reflect the views, at the time of publication, of PETRONAS OPUs/Divisions. They are based on the experience acquired during the involvement with the design, construction, operation and maintenance of processing units and facilities. Where appropriate they are based on, or reference is made to, national and international standards and codes of practice. The objective is to set the recommended standard for good technical practice to be applied by PETRONAS' OPUs in oil and gas production facilities, refineries, gas processing plants, chemical plants, marketing facilities or any other such facility, and thereby to achieve maximum technical and economic benefit from standardisation. The information set forth in these publications is provided to users for their consideration and decision to implement. This is of particular importance where PTS may not cover every requirement or diversity of condition at each locality. The system of PTS is expected to be sufficiently flexible to allow individual operating units to adapt the information set forth in PTS to their own environment and requirements. When Contractors or Manufacturers/Suppliers use PTS they shall be solely responsible for the quality of work and the attainment of the required design and engineering standards. In particular, for those requirements not specifically covered, the Principal will expect them to follow those design and engineering practices which will achieve the same level of integrity as reflected in the PTS. If in doubt, the Contractor or Manufacturer/Supplier shall, without detracting from his own responsibility, consult the Principal or its technical advisor. The right to use PTS rests with three categories of users : 1) 2) 3)

PETRONAS and its affiliates. Other parties who are authorised to use PTS subject to appropriate contractual arrangements. Contractors/subcontractors and Manufacturers/Suppliers under a contract with users referred to under 1) and 2) which requires that tenders for projects, materials supplied or - generally - work performed on behalf of the said users comply with the relevant standards.

Subject to any particular terms and conditions as may be set forth in specific agreements with users, PETRONAS disclaims any liability of whatsoever nature for any damage (including injury or death) suffered by any company or person whomsoever as a result of or in connection with the use, application or implementation of any PTS, combination of PTS or any part thereof. The benefit of this disclaimer shall inure in all respects to PETRONAS and/or any company affiliated to PETRONAS that may issue PTS or require the use of PTS. Without prejudice to any specific terms in respect of confidentiality under relevant contractual arrangements, PTS shall not, without the prior written consent of PETRONAS, be disclosed by users to any company or person whomsoever and the PTS shall be used exclusively for the purpose they have been provided to the user. They shall be returned after use, including any copies which shall only be made by users with the express prior written consent of PETRONAS. The copyright of PTS vests in PETRONAS. Users shall arrange for PTS to be held in safe custody and PETRONAS may at any time require information satisfactory to PETRONAS in order to ascertain how users implement this requirement.

GUIDELINES FOR CALCULATING SAFETY DISTANCES IN LPG STORAGE AND HANDLING INSTALLATIONS CONTENTS 1.

Introduction

2.

Assessment of Fire Situations

3.

4.

5.

2.1

Audit of the Facilities

2.2

Selection of Leakage Scenarios and Assessment of their Consequences

2.3

Radiation Criteria for Personnel Protection

2.4

Vapour Cloud Explosion

2.5

Boiling Liquid Expanding Vapour Explosion (BLEVE)

2.6

Selection of Leak Reduction Measures and Methods to Mitigate the Effects

Consequence Assessments 3.1

Introduction

3.2

Calculation of Flow Rates

3.3

Vapour Jets - Dispersion and Fires

3.4

Two-phase Jets - Dispersion and Fires

Worked Example 4.1

Description of Facility

4.2

Audit of the Facility and Choice of Scenarios

4.3

Consequence Assessment, Analysis and Proposed Action

References

TABLES 1.

Discharge Areas for 'REGO'. 'FISHER', and other pressure relief valves

2.

Relief Valve Fire and Radiation Flux Data for Propane

3.

Relief Valve Fire and Radiation Flux Data for Butane

FIGURES 1.

Schematic of Model Facilities

2.

Example PLUMEPATH Dispersion Profile for Butane

3.

Distances to LFL for Propane and Butane Releases

4.

Distances to 1.5 kW/m² Radiation Flux for Vapour and Liquid Horizontal Butane Jet Fires

5.

Distances to 5 kW/m² Radiation Flux for Vapour and Liquid Horizontal Butane Jet Fires

6.

Distances to 8 kW/m² Radiation Flux for Vapour and Liquid Horizontal Butane Jet Fires

7.

Distances to 13 kW/m² Radiation Flux for Vapour and Liquid Horizontal Butane Jet Fires

8.

Distances to 32 kW/m² Radiation Flux for Vapour and Liquid Horizontal Butane Jet Fires

9.

Distances to 44 kW/m² Radiation Flux for Vapour and Liquid Horizontal Butane Jet Fires

10.

Flame Lengths for Vapour and Liquid Horizontal Butane Jet Fires

11.

Distances to 1.5 kW/m² Radiation Flux for Vapour and Liquid Vertical Butane Jet Fires

12.

Distances to 5 kW/m² Radiation Flux for Vapour and Liquid Vertical Butane Jet Fires

13.

Distances to 8 kW/m² Radiation Flux for Vapour and Liquid Vertical Butane Jet Fires

14.

Distances to 13 kW/m² Radiation Flux for Vapour and Liquid Vertical Butane Jet Fires

15.

Distances to 32 kW/m² Radiation Flux for Vapour and Liquid Vertical Butane Jet Fires

16.

Distances to 44 kW/m² Radiation Flux for Vapour and Liquid Vertical Butane Jet Fires

17 .

LPG Depot Layout - Worked Example

18.

Flow scheme - Worked Example

19.

Nozzle details of Propane Sphere Worked Example

20.

Nozzle details of Butane Sphere Worked Example

1.

INTRODUCTION One of the main differences between the recently-issued Supply and Marketing (SM) LPG Manual P a r t 2 S e c t i o n 0 3 P T S 3 0 . 0 6 . 1 0 . 1 2 . L P G B u l k S t o r a g e Installations (hereafter referred to as the Manual/PTS) and previous issues is the requirement to relate siting of equipment to the radiation flux levels that would be experienced from fires in the installation. This approach applies to LPG bulk storage installations with individual tanks of 135 m3 and above and is consistent with the Institute of Petroleum Model Code of Safe Practice, Part 9, Liquefied Petroleum Gas, Volume 1, dated February 1987. The covering letter which was sent to all companies with the Manual/PTS suggested that all sites should compare the design of their facilities with the new standards and consider whether any aspects should be modified. Site layout is one aspect that in many cases will be difficult, if not impossible, to alter. Therefore, it will be important to examine whether a fire could endanger human life, equipment or property, inside or outside the site. If this is recognized as a possibility, it will be necessary to consider changes to the design to reduce the probability of the incident and/or provide additional protection to people and equipment. In a completely unacceptable situation it may be necessary to shut down the installation and transfer the activities elsewhere. Since the Manual/PTS does not indicate how the evaluation should be carried out, or provide information on the calculation of thermal radiation levels, an inter-functional team has produced this set of guide-lines with the assistance of Thornton Research Centre. It has been written in three parts: Section 2.

Assessment of Fire Situations

Section 3.

Consequence Assessments

Section 4.

Worked Example

It should be noted that although these guide-lines have been produced as an aid for evaluating the layout requirements for bulk storage installations with individual tanks of 135 m3 and above, they are also in general applicable to layout aspects of all other sections of plants handling pressurized LPG at Marketing and Manufacturing installations (e.g. loading/ unloading ships, bulk road vehicles or rail tank wagons and filling cylinders). As stated in the Manual/PTS, operating companies may choose to apply these guidelines to installations with 3 individual tanks of less than 135 m .

2.

ASSESSMENT OF FIRE SITUATIONS

2.1

AUDIT OF THE FACILITIES Section 03.02.01.02 of the Manual/PTS covers safety distances. It states that possible leak sources should be identified and their rate of leakage and duration assessed. The first step is the identification of such leak sources. This requires a systematic evaluation of the design against the Manual/PTS and a review of the operating/maintenance procedures for the installation. The assessment should be carried out by a team of three or four people, who between them have a good knowledge of the design, operation and maintenance of the facility. They should have available up-to-date flow schemes and engineering information about the equipment before they start. The team should study the facility, line by line and piece of equipment by piece of equipment, and consider whether there could be any circumstances which might lead to a leak of LPG. This should be done in an imaginative way with the team considering the usual operating conditions at the site and also any unusual conditions which they can conceive. They would consider, for instance:

− possible high or low temperatures − possible high or low pressures − overfilling of storage vessels, bulk lorries or rail tank wagons − the effect of impurities in the LPG (e.g. water) − the wrong grade of LPG (e.g. C3 instead of C4) − the effect of incorrect operation or maintenance − incorrect material selection or equipment fabrication − malfunctioning equipment − impact (e.g. vehicles) The procedure outlined above is a simplified version of the more structured HAZOP study, where the team leader takes the team through a series of guide words for each part of the plant which they are examining. 2.2

SELECTION OF CONSEQUENCES

LEAKAGE

SCENARIOS

AND

ASSESSMENT

OF

THEIR

In section 03.02.01.02 (c) of the Manual/PTS it states that the evaluation of leak sources should take into account failure modes, likelihood and consequences. It is not possible to give detailed guidance on the likelihood of particular leak scenarios, because the probability that an event will occur will depend on the design of the specific facility and the quality of its operation and maintenance. However, a review of serious incidents that have occurred in the LPG industry shows that they have usually been the result of the following situations:

− Product discharge through a relief valve (including overfill). The Manual/PTS requires in section 03.02.01.02 (a) that product discharge to atmosphere through relief valves on LPG storage vessels should be considered as leakage scenarios in all cases. This requirement is consistent with the Institute of Petroleum Model Code of Safe Practice, Liquid Petroleum Gas, Volume 1. The rationale behind this requirement is that these relief valves are the only devices in an LPG facility which are designed to be able to vent large quantities of LPG to atmosphere.

− Flange leak or other joint leak (see Section 4 for typical leakage hole sizes) − Pump seal leak (see Section 4 for typical leakage hole sizes) − Open drain valve − Rupture of small bore connections (e.g. breakage of an instrument line) − Hose leak or rupture (e.g. vehicle pullaway) It is recommended that these failure modes should always be considered for consequence calculations, unless the audit team has very good reasons to discount them. Other situations will be possible on many installations. These could include the leak of a vessel or pipeline due to internal or external corrosion, or the effect of an external incident such as vehicle impact. Inclusion of these scenarios for consequence calculations will depend on the team's judgement of whether their likelihood is greater or less than that of the failure modes listed above. Using the information given in Section 3 the team should next assess the flow rate of the leaking liquid or vapour. Factors in the design which may control the flow should be taken into account. An assessment should also be made of the time that the release will last. This will depend on the presence of operators, the accessibility of manually-operated isolating valves and the existence of remotely-operated valves. The likelihood of ignition will depend in part on the time that a flammable mixture persists. When a leak or spill occurs the hydrocarbon vapour will disperse, forming a cloud. The distances to the lower flammable limit can be obtained from Section 3. Should the cloud extend beyond the site boundary or to another area where ignition sources are not controlled, measures will be necessary to limit the size of the release. Flash calculations for liquid butane and propane suggest that product leaks may form significant liquid pools. However, experimental work and field trial studies by Thornton Research Centre have established that the jet formed when these materials are released entrains considerable amounts of air. Small droplets of liquid LPG are formed. These evaporate rapidly and the result is a cold vapour cloud with no significant pool formation. The only situation for which pool formation can be envisaged is with butane in cold climates when its vapour pressure is low. At the same time the discharge velocity must be low, as in the case of a leak in the discharge line from a storage vessel, when the driving force is provided largely by the head in the vessel. Therefore, in nearly all leakage situations ignition of the leak will result in a jet fire, rather than a pool fire. Finally the distances to various levels of radiation intensity from ignited leaks can be read from the tables associated with Section 3. The results should then be compared with the criteria given in Figure 03.02.01.02 of the Manual/PTS, which are discussed in Section 2.3. 2.3

RADIATION CRITERIA FOR PERSONNEL PROTECTION In Figure 03.02.01.02 of the Manual/PTS maximum radiation flux levels are given for personnel inside the site boundary and for the situation at the site fence. The notes attached to this figure only give brief guidance on the choice of type of area. In order to give additional guidance the following amplified notes have been prepared. The acceptability of maximum heat flux levels is based, in part, on the person's ability to escape, since injury is a function of heat flux and exposure time. Employees engaged in the location's activities should be trained in what to do in an emergency and will be healthy and active. On the other hand, members of the public at or near a location are unlikely to know what to do and may also include the full community age and health range.

2.3.1

Plant boundary situations

− Remote Area. An area where there is a low likelihood of people. Those likely to be −

present will be fit but may be lightly clothed. There is no shelter available but escape is both easy and obvious. Urban Area. An area where there is a strong possibility of people of full community age and health range being present. They will be fully clothed. There is no shelter available but escape is easy or only slightly hindered (e.g. need to cross a road).

In a situation where there is no site fence, such as an automotive LPG station, it may be necessary to relate the size of the fire to the time needed to get away from the heat. For instance, not more than 30 seconds should be required to move from a radiation intensity of 5 kilowatts/ metre² (kW/sq.m) (second degree burns in ca. 30 secs) to an intensity of 3 kW/sq.m (second degree burns in 60 secs) and a further 90 seconds to get to an intensity of 1.5 kW/sq.m.

− Critical Area. This is the same as an urban area, but with hindered means of escape. 2.3.2

2.3.3

Plant areas −

Process Area. Those likely to be present will be healthy and trained in emergency procedures. They will be fully clothed and will be able to be clear of the area within one minute.

−

Protected Work Area. This refers to permanent buildings where personnel are obliged to remain in order to operate plant, but may be exposed through glass. It may also provide a refuge for those escaping from the fire. The radiation level refers to the building exposure.

−

Work Area. There is minimal shelter from the fire and slightly hindered escape. Those present will be healthy and be fully clothed.

−

Critical Area. This is one where an operator may have to be present for short times occasionally, e.g. to check the state of equipment. He will be trained in what to do if a fire starts, but escape routes may be hindered because of plant complexity.

Flash fires When a cloud of hydrocarbon vapour ignites the initial flash fire will be of high intensity, but of such a short duration that only people actually enveloped in it will be seriously burnt.

2.4

VAPOUR CLOUD EXPLOSION If an LPG installation is designed to the current Manual/PTS and other Group standards for handling LPG, or has been adequately updated, the probability of a leak or spill being large enough to result in an explosion will be very low. In addition, trials carried out by research organizations have shown that vapour cloud explosions in an open situation are very unlikely. If LPG vapour enters an area where equipment or pipework are closely spaced, or enters a building, drainage system or another confined space, an explosion may well be possible. Vapour cloud explosion is a complicated subject, and is still an active research topic. If a company considers that it is necessary to review the possibility of such an event, it should consult CHSE for advice.

2.5

BOILING LIQUID EXPANDING VAPOUR EXPLOSION (BLEVE) This type of explosion occurs when a ductile vessel, containing a liquid whose vapour pressure is well above atmospheric, ruptures. Because the vessel is made of a ductile material its shell tears, generating a relatively small number of large fragments. If the liquid in the vessel is flammable and the rupture has been caused by heat from an external fire weakening the wall of the vessel above liquid level, the BLEVE produces a buoyant fireball. The size of the fireball, its duration and the intensity of its radiation are determined by the total contents of the product in the vessel. The pieces of the vessel can travel several hundreds of metres. This is the situation usually associated with the occurrence of a BLEVE. In the past a BLEVE has been considered as an unrealistic event for an installation designed to Group standards. However, it must be recognized that BLEVEs occur somewhere in the world, either with transport tanks or in fixed installations, at the rate of about one every two years. Therefore, the possibility has to be recognized, particularly by PETRONAS companies with older installations .

If the installation meets the requirements of the Manual/PTS the probability of a BLEVE will be low enough to be considered unrealistic, because these standards have been developed specifically to eliminate the possibility of the vessel walls being overheated. However, if some of the requirements are not met and/or if operating procedures are not strictly enforced, the probability could be much higher. A critical review of the design, operation and maintenance of the installation should be carried out if any concern is felt by a company. CHSE would be prepared to assist in such a review. Another possible cause of vessel failure is severe over pressurization, probably associated with vessel imperfections due to faults in the material of construction, faults in its fabrication, or possibly due to internal corrosion. Failure for these reasons is considered extremely unlikely for a vessel installed to the requirements of the Manual/PTS and operated correctly. If a source of ignition is also present a fireball similar to that produced by a BLEVE will occur. 2.6

SELECTION OF LEAK REDUCTION MEASURES AND METHODS TO MITIGATE THE EFFECTS If any of the leakage scenarios that have been examined are found to give unacceptable radiation levels at the site boundary or within the facility it will be necessary to consider measures that will either reduce the probability of the release, reduce its length of time, or reduce the radiation level. In the first place the requirements of the Manual/PTS should be applied. However, if these are not practicable other methods may be considered. The suggestions given below are not exhaustive; some will be more suitable for Marketing locations, while others may be preferred by Manufacturing locations. It must be recognized that there may be occasions when it is not practicable to improve the installation to an adequate level of safety. In that case it may be, necessary to shut down or relocate the facilities. −

Installing hydrocarbon gas detectors/alarms, possibly interconnected to emergency shut down valves.

−

Incorporating fusible links in the actuating systems for emergency shut down valves.

−

Installing secondary emergency shut down valves with a mode of failure non-common to the primary valves.

−

Welding more of the pipework and valves.

−

Connecting all relief valves to a flare or vent system.

−

Providing fire protection/tank cooling for small tanks as well as for large tanks.

−

Providing fire protection for adjacent equipment.

−

Pressurization or sealing of nearby buildings containing sources of ignition (e.g. an electrical substation).

−

Using breakaway couplings or drive-away protection in road and rail tank filling/discharge systems.

−

Installing vehicle impact barriers.

−

Using load cells/weigh bridge to reduce the chance of overfilling bulk lorries or rail tank wagons.

−

Using computer controlled loading/unloading.

−

Replacing hoses with loading arms.

−

Using mounded storage at new sites.

3.

CONSEQUENCE ASSESSMENTS

3.1

INTRODUCTION This part of the Guide-lines provides a range of dispersion and fire hazard assessments to complement the leakage scenarios described in Section 2. The structure which has been adopted is intended to mirror the main classes of hazard which can arise, which are vapour and two-phase jet releases. However, a prerequisite for carrying out dispersion and fire hazard assessments is the calculation of the relevant mass flow rates. The three resulting sections are headed:

3.2

−

Calculation of flow rates

−

Vapour jets, dispersion and fires

−

Two-phase jets, dispersion and fires

- vapour leakage flows - liquid leakage flows

CALCULATION OF FLOW RATES The following sections provide calculation methods for most leakage situations. For a general treatment of the calculation of leakage flows, the reader is referred to the review written by Ramskill and entitled "Discharge rate calculation methods for use in plant safety assessments" (Ref. 1). The leakage from equipment at LPG installations will be of two types. It may come from the vapour space of vessels or from lines handling LPG vapour. when only vapour flow has to be considered. Alternatively, the leak may be from lines or equipment handling liquid LPG. In these cases liquid flow or two-phase flow may occur. Vapour leakage flow calculations and liquid/two-phase flow calculations are described in the following subsections.

3.2.1

Vapour leakage flows Vapour leakage flows may be divided into two categories: −

Flow through relief valves and other cases where choked flow occurs.

−

Flow through holes where choked flow does not occur.

Choked flow occurs where the ratio of upstream and down-stream pressure is greater than a critical value. For propane and butane this occurs where:

Pr essure in pipe or vessel ≥ 1.8 Atmospheric pressure In practice this will be the likely situation at many installations. For ease of calculation it is recommended that all vapour leaks are treated as choked flow and handled as described below, although this may be a conservative assumption. If required, calculation methods for unchoked flow can be found in Reference 1. These flows should be sufficiently accurate for most leakage situations. However, in complex cases, e.g. where there is a large hole in a pipe which is more than, say, 20 m from the vessel which is the source of pressure, pipe friction losses will reduce the flow rate. In these cases reference should be made to the review by Ramskill (Ref. 1). The calculation of choked flow is demonstrated by the operation of a relief valve. The relief valve on a partly filled vessel of LPG will open as soon as the pressure in the vapour space of the vessel has risen to the relief valve set pressure. This could for example be due to the effect of a fire close to the vessel. The formula to be used for the flow calculation is that derived from API RP 520 - "Recommended Practice for the Design and Installation of Pressure Receiving Systems in Refineries" (Ref. 2). The equation is derived from a general equation for conditions of critical flow and may be written:

W=

KAP M C T

(1)

where: W is the flow rate (Kg/s), C is the gas/vapour constant, K is the discharge coefficient, A is the discharge area (m²), P is the vessel design pressure x 1.2 (N/m²), (or upstream pressure for holes in equipment) M is the molecular weight, T is the relief valve inlet temperature (K). The value of C is 145 for propane and butane. The discharge coefficient (K) of a relief valve varies with the inlet and disc shape and also lift characteristics. It should be taken as 0.9. Tables 1(A), (B) and (C) give the discharge area (A) for typical relief valves. Equation (1) may also be used for vapour flow through holes in equipment. In this case the value for the discharge coefficient (K) should be 0.8. For the case of tanks affected by fire, equation 1 reduces to the following working equations (2) + (3): For propane tanks: W=

KAP (Kg/s) 419

(2)

For butane tanks: W=

KAP (Kg/s) 367

(3)

In this case the relief valve inlet temperature (T) has been taken as 100°C, not the equilibrium temperature for the pressure at which the relief valve is blowing. The temperature of 100°C is based on experimental fire engulfment trials. 3.2.2

Liquid leakage flows Simple liquid flows may generally be calculated by the use of Bernoulli's equation. Examples include leaks at temperatures well below the boiling point, or orifice type leaks driven by the product head. In general, however, leakage flows will be two phase in nature with varying vapour to liquid ratios. Propane and propane/butane mixtures are generally handled as liquids well above their atmospheric boiling points, so that a large fraction will flash during emission. With butane, however, it is more likely that on occasion the temperature may fall below its boiling point at atmospheric pressure. Whilst this condition increases the likelihood that the leakage flow has a higher liquid percentage, significant vapour emission will still arise. This may be understood by examining Figure 01.02.08.01 of the Manual/PTS, which shows the absolute vapour pressures of those light hydrocarbons which are the principal components of commercial LPG. In general terms, the calculation of flashing LPG flows from pressurized systems is complex since rapid evaporation of the liquid can take place before, during and after emission. The precise form of emission, pipe rupture, flange leak, valve leak, hose burst, etc., can play a major part in conditioning the resultant flow. For simplicity the equations presented in these Guidelines are adequate for nearly all leakage situations that an assessment team could meet. More generally, however, the calculation of two phase flows is complex so that where greater precision in calculation becomes important the matter should be referred to PETRONAS.

Appendix 3 of the Institute of Petroleum Model Code of Safe Practice, Part 9, Liquefied Petroleum Gas, Volume 1, describes the calculation of release rates based on the application of a typical simple equation which assumes a homogeneous equilibrium two-phase flashing liquid release from the orifice. The discharge coefficient has been taken as 1.0. These assumptions will obviously produce leakage rates at variance with those calculated using the equations set out herein. 3.2.2.1 Overflows through relief valve vents This case can arise when the relief valve opens as a result of product being pumped into the vessel after it is full. Maximum liquid flow rate into the vessel should be used for the consequence calculations. It is recommended that the capacity of the relief valve is checked for this flow, since changes to the LPG handling system may have been made since the system was designed. The recommended method is to be found in section 3.17 of API RP 521. The flow formulae to be used are presented in Appendix C of API RP 520 (Ref. 3). 3.2.2.2 Flows from broken equipment When pressurized LPG is released from containment the discharge is usually a two-phase mixture of vapour and liquid. The behaviour of such a discharge is difficult to analyse and not fully understood. There is a maximum discharge rate which exists for a two-phase mixture. This occurs at some critical pressure ratio between the upstream pressure and the exit pressure. Several methods have been proposed to evaluate the critical discharge rate of a two-phase flow from a pipe. Here the simple equations described in Ramskill's review are used . The equation to be used is dependent on the length/diameter ratio (L/D) of the leakage path. In all the equations used here the discharge coefficient is taken as 0.6. Three leakage path situations may be considered: For L/D = 0 We have orifice flow and the flow rate is described by:

M = 0.6 A

2 ρ (Po − Pa )

(4)

where M Po Pa A

ρ

is mass flow rate (kg/s) 2 is upstream pressure (N/m ) 2 is atmospheric pressure (N/m ) 2 is area of hole (m ) 3 is density (kg/m )

Examples of this situation are small holes in pipes or equipment, e.g. due to corrosion For 0 < L/D 12 Pc = 0.55 Po For Po choose equilibrium vapour pressure at 15°C = 5

2

9 x 10 N/m (Ref Fig 01.02.08.01 of Manual /PTS) Pc = 0.55 x 9 x10

5

5

= 4.9 x 10 N/m2 Tc = 268°K m = 1 – exp [

−c ( T1 – Tc)] λ

with c = 2 407 J/kg°K (Ref Fig 01.02.11.01 of Manual /PTS) and λ = 383 000 J/Kg (Ref Fig 01.02.10.01 of Manual /PTS) m = 1 - exp

 − 2 407   383 000 ( 288 − 268)  

= 0.12

 m 1− m  Mixture density ρc =  + ρ1   ρg

−1

. 0.88   012 + ρc =    9.3 535 

−1

(Ref Tables 01.02.04.01 and 01.02.0.03. of Manual /PTS.) 3 = 69kg/m

Critical flow rate M = 0.6 A

2 ρ c (Po − Pc )

π x 0.12 = 0.6 x 4

2 x 69 (9 x 105 − 4.9 x 105 )

= 35.4 kg/sec

From Figure 3 estimate distance to LFL as follows: 5D conditions - 105 m 2F conditions - 190 m Probability of early ignition is high. Vehicles on motorway most likely ignition source. From Figures 4 to 16 distances to radiation flux levels from the ignited mixture are as follows: Horizontal Jet Fires

Vertical Jet Fires

1.5 kW/m²

140 m

120 m

5 kW/m²

110 m

65 m

13 kW/m²

90 m

40 m

This scenario is clearly unacceptable, even though the leak considered above is fed by the barge storage alone. The leakage rate would be much greater if the shore based pipelines were also to contribute to the leak. The consequences of this incident are so severe that the leakage rate and duration should be reduced. The probability of the incident should also be reduced. Possible means of achieving the above are:

4.3.2

•

Emergency release couplings on loading arms.

•

An inter-related system of remotely-operated fail-safe emergency shutdown valves at the termination of the barge pipework and on the berth on the shore side of the loading arms.

•

Inclusion of fusible links in emergency shutdown systems.

•

Supervision during entire unloading operation at the berth.

•

Improved fire protection/fire fighting and gas detection/ gas dispersion facilities.

•

Construction of a water curtain adjacent to the motorway.

Scenario 2: Flange., swivel joint, or small-bore connection leak at barge loading berth In this scenario, typically consider one segment of a flange gasket blown out. Based on a number of pipe sizes from 50 mm to 300 mm diameter. the average leakage path area equates to an effective hole diameter of 12 mm. A small-bore connection leak would give a similar case. As above, the calculation is only completed for the propane case. From Section 3.2.2.2 Adopt L/D = 0 M = 0.6A

2ρ (Po − Pa )

π x 0.012 2 = 0.6 x 4 = 2.0 kg/sec

2 x 510 (9 x 105 − 1 x 105 )

From Figure 3 estimate distance to LFL as follows: 5D conditions - 25 m 2F conditions - 35 m. The elevation of the barge berth is lower than the motorway and the berth is elevated above the river. The above distances will therefore be conservative because LPG vapour is heavier than air and the vapour will tend to fall to the river. From Figs 4 to 16 distances to radiation flux levels from liquid fires are as follows: Horizontal Jet Fires

Vertical Jet Fires

1.5 kW/m² 5 kW/m²

55 m 40 m

45 m 30 m

8 kW/m²

40 m

25 m

13 kW/m²

35 m

20 m

The scenario is unacceptable. The radiation flux levels on the motorway particularly are excessive. The probability of leakage should be reduced. The pipework in the barge berth area contains many joints and small bore connections. Possible action to reduce the probability of leakage includes: •

Rationalisation of pipework to reduce number of joints/ connections.

•

Replace flanged joints with welded joints.

In addition, possible action to prevent the vapour cloud reaching the motorway and/or to protect the motorway from the effects of an ignited leak includes:

4.3.3

•

Construction of vapour barrier wall.

•

Installation of water curtain with or without automatic actuation triggered by gas detectors on the berth.

Scenario 3: Damage to pipelines due to vehicular or vehicular goods impact In this scenario the range of damage caused by impact could range from shearing the pipelines to springing a flange. Typical leakage rates for these two extremes have already been considered in the above two scenarios. As both the above scenarios are unacceptable then this scenario is also unacceptable. Possible actions are:

4.3.4

•

Install reinforced highway guard-railing adjacent to pipe track.

•

Bury pipelines in this area.

•

Install remote operated emergency shutdown valves at either end of vulnerable pipework.

Scenario 4: Flange leak on pipe track The leakage rate in this scenario will be as for the similar case at the barge berth (i.e. M = 2.0 kg/sec). Where the pipelines enter the depot there is significant local confinement, especially in a disused compressor shed. Confinement raises the possibility of vapour cloud explosion in the event of ignition. The probability of ignition is high due to the adjacent motorway and offices. This scenario is unacceptable. Possible actions: •

Reduce probability of leakage as for Scenario 2.

•

Examine need for disused building and demolish if possible and/or investigate other means to reduce confinement.

4.3.5

Scenario 5: Propane delivered into butane rated spheres In order to calculate the vapour pressure of a mixture created by delivering propane into the butane spheres, a worst case of assuming 100 per cent propane at a receipt temperature of 25°C into an empty sphere has been adopted. 5

The vapour pressure of propane at 25°C is 11.5 x 10 N/m² which is higher than the 5 design pressure of the butane sphere of 7.3 x 10 N/m² . This is also the start-todischarge pressure of the relief valves. The fully open pressure (accumulated pressure) is 5 8.0 x 10 N/m². The scenario is unacceptable. If product contamination is a credible scenario, then the relief valves should be sized to relieve sufficient propane vapour to avoid overpressurization of the vessel. Possible actions to prevent product contamination are:

4.3.6

•

Clear and positive identification of pipelines throughout the depot and particularly at the barge berth.

•

Introduction of a valve interlock system to ensure only one set of valves is open at the barge berth.

•

Installation of in-line densitometers linked to an alarm/ shutdown system to detect incorrect product in pipelines.

Scenario 6: Leaks from flanged Joints on butane spheres on sphere side of primary valve The leakage in this scenario will again be based on leakage from an equivalent hole diameter of 12 mm. From Scenario 2

2ρ (Po − Pa )

M = 0.6A

= 0.6 x

π x 0.012 2 4

2 x 577

(3.1 x 10 5 − 1 x 10 5 )

= 1.1 kg/sec From Figure 3 estimate distance to LFL as follows: 5D conditions - 15 m 2F conditions - 25 m From Figs 4, 5, 6, 7, 9 distances to radiation flux levels from liquid fires are: Horizontal Jet Fires 1.5 kW/m²

40 m

5 kW/m²

30 m

8 kW/m²

25 m

13 kW/m²

25 m

44 kW/m²

20 m

Vertical jet fires will impinge on the vessel shell in all cases. No radiation distances are therefore given. In the event of ignition the radiation effects on the sphere and on adjacent spheres exceed 44 kW/m² and are therefore unacceptable. Possible actions to reduce the probability of this scenario are: •

Modification to sphere pipework and provision of correct valve to remove flanged joint upstream of primary valve.

4.3.7

Scenario 7: Vapour release from butane sphere pressure relief valve From Section 3.2.1, for fire-engulfed butane tanks W=

KAP kg/sec 367

Spheres are equipped with two pressure relief valves although only one valve is lined up at any time. The valves are labelled as 6R10. From Table 1c for R orifice, -4

Discharge area = 103.23 x 10 m² W=

0.9 x 103.23 x 10 −4 x 7.3 x 12 . x 105 367

= 22.2 kg/sec. Section 3.3.1.1 describes that flammable vapour plumes from vertical relief valves may be assumed not to reach ground level. The distance to LFL is therefore not applicable in this instance. From Table 3, distance downwind to radiation flux levels are: Tank Top Radiation Flux 8 kW/m² 44 kW/m²

-

45m -

Ground Level Radiation Flux 1.5 kW/m² 5 kW/m² 13 kW/m²

-

95 m 40 m -

The above flux levels indicate that the 5 kW/m² radiation contour crosses the site boundary. Whilst this boundary should probably be described as an urban area, the region adjacent to the boundary is not developed and a higher radiation intensity could be tolerated. Given that the flux level at the plant boundary is not much greater than 5 kW/m², this scenario is considered to be acceptable and the existing location of the butane sphere closest to the plant boundary does not warrant any action. Any future development outside the plant should be monitored as construction of a hospital, school or other facility difficult to evacuate at short notice would require a reappraisal of the situation. 4.3.8

Scenario 8: Overfill of propane/butane spheres Overfill of the propane or butane spheres will not result in product leakage from the spheres but will result in liquid flow through the suction line to the compressor. A liquid stroke in the compressor is unacceptable. Possible actions are:

4.3.9

•

Installation of remote readout level gauge in transfer control area.

•

Installation of level gauge capable of registering low level, high level and high-high level, with alarms and inlet valve shutdown devices attached. Gauges should permit regular testing to ensure satisfactory operation.

•

Regular testing of maximum fill level gauge.

•

Installation of liquid level emergency alarm on knockout drum with compressor trip.

Scenario 9: Leak from flanged joint on propane sphere on sphere side of primary valve This scenario as per Scenario 2: M = 2.0 kg/sec. Distances to LFL: 5D conditions - 25 m 2F conditions - 35 m

Distances to radiation flux levels from liquid fires are: Vertical Jet Fires

Horizontal Jet Fires 1.5 kW/m²

55 m

45 m

5kW/m²

40 m

30 m

8 kW/m²

40 m

25 m

13 kW/m²

35 m

20 m

44 kW/m²

30 m

10 m

The radiation flux level on the propane sphere in the event of an ignited leak is excessive, although the location of the primary valve remote from the sphere mitigates the impact on the sphere. Possible actions are as for Scenario 6. 4.3.10 Scenario 10: Vapour release from propane sphere pressure relief valve due to fire engulfment From Section 3.2.1 for fire engulfed propane tanks: W=

KAP kg/sec 419

The propane sphere is equipped as per the butane spheres with two pressure relief valves although only one is lined up at any time. The valve is labelled 6R10. From Table 1C for R orifice: -4

Discharge area = 103.23 x 10 m²

0.9 x 103.23 x 10 −4 x 15.5 x 12 . x 105 W= 419 = 41.2 kg/sec As for the butane case, the distance to LFL is not applicable as the flammable plume may be assumed not to reach ground level. From Table 2, distance downwind to radiation flux levels are: Tank top Radiation flux 8 kW/m² 44 kW/m²

-

50 m -

Ground level radiation flux: 1.5 kW/m² 5 kW/m² 13 kW/m²

-

110 40 2

As for the butane case, the 5 KW/m radiation contour crosses the site boundary, The figures are similar for both the propone and butane case and the points set out for the butane case are therefore also applicable to this case. 4.3.11 Scenario 11: Leak from pump seal due to total failure of seal Adopt L/D = 0 For pumps without throttle bushing, adopt effective diameter hole =17mm M = 0.6A (a)

2ρ (Po − Pa ) )

For Propane

M = 0.6 x

π x 0.017 2 4

= 4.0 kg/sec

2 x 510

(9 x 105 − 1 x 105 ))

From Figure 3 estimate distance to radiation flux levels from liquid fires are : 5D condition – 35m 2F condition – 55m From Figures 4 to 16 distances to radiation flux levels from liquid fires are:

(b)

Horizontal Jet Fires

Vertical Jet Fires

1.5 kW/m²

80 m

65 m

5

kW/m²

60 m

45 m

8

kW/m²

55 m

40 m

13 kW/m²

50 m

30 m

44 kW/m²

45m

15 m

For butane M = 0.6 x

π x 0.017 2 4

2 x 577 (31 . x 105 − 1 x 105 )

= 2.2 kg/sec From Figure 3 estimate distance to LFL as follows: 5D condition – 25m 2F condition – 35m From Figures 4 to 16 distances to radiation flux levels from liquid fires are: Horizontal Jet Fires

Vertical Jet Fires

1.5 kW/m²

60 m

50 m

5

kW/m²

45 m

30 m

8

kW/m²

40 m

25 m

13 kW/m²

35 m

20 m

44 kW/m²

30 m

10 m

The transfer pumps are positioned at three locations in the depot. The propane pump has the greatest potential for impact outside the depot whereas the butane pumps have greater potential for internal impact. The vapour cloud from the propane pump seal failure extends well beyond the depot boundary. Ignition of this leak gives radiation flux levels which are unacceptable beyond the plant boundary. The flux levels from the butane pump seal failure within the depot are also unacceptable for process, protected work and work areas. Possible actions are: •

Installation of throttle bushes. This has the effect of reducing effective hole diameter from 17 mm to 10 mm.

•

Installation of improved integrity seals (e.g. double mechanical seals).

•

Review of operating and maintenance procedures to ensure rotating equipment is regularly inspected and serviced.

4.3.12 Scenario 12: Flange, small bore connection leak at compressor station This consequences of this scenario are similar to those of Scenario 2. A leak in this area could well see the vapour cloud extend into the residential area where the probability of ignition is high. The flux levels from an ignited release impinging on the residential area are excessive and action is required to reduce the probability of leakage and/or reduce flux levels in the residential area. Possible actions are: •

Reduce probability of leakage as for Scenario 2.

•

Construction of fire wall or water curtain at property boundary to limit flux levels beyond the boundary.

4.3.13 Scenario 13: Bulk road vehicle loading am rupture As in Scenario 1 this situation has only been calculated for propane. From typical vehicle loading pump performance chart, the maximum discharge rate against zero pump differential is approximately 4 kg/sec. This rate is clearly the limiting factor in this scenario for leakage fed from the depot pipelines. However the leak can also be fed from the bulk vehicle and there is no such limiting factor from this source. Leak = Two-phase leak from 76 mm dia hole Conditions for this scenario are similar to Scenario 1 thus ρ c = 69 kg/m3 Critical flow rate

2ρc(Po − Pc )

M = 0.6A

= 0.6 x

π x 0.0762 4

2 x 69 (9 x 105 − 4.9 x 105 )

= 20.5 kg/sec From Figure 3 estimate distance to LFL: 5D conditions - 75 m 2F conditions - 140 m Probability of ignition is high as LFL extends well beyond site boundary and into housing area on eastern side of depot. From Figures 4 to 16 distances to radiation flux levels from the ignited mixture are:

1.5 kW/m² 5

kW/m²

13

kW/m²

Horizontal Jet Fires

Vertical Jet Fires

110 m

95 m

85 m

55 m

70 m

30 m

This scenario is unacceptable. As for Scenario 1, the probability of the incident and also the leakage rate from the incident should be reduced. Possible means of achieving the above are: •

Breakaway couplings.

•

Driveaway prevention device(s) on the bulk road vehicle or installed as part of fixed facility (e.g. boom).

•

Remote-operated emergency shutdown system capable of operating valves on both delivery pipeline and bulk road vehicle.

•

Fusible links in emergency shutdown system.

•

Increased supervision during loading.

•

Improved fire-fighting/fire protection and gas detection/ dispersion facilities (e.g. automatic sprinkler system over loading bay).

4.3.14 Scenario 14: Flange, swivel joint, or small bore connection leak at bulk vehicle loading point This consequences of this scenario are similar to those of Scenario 2. The distances to LFL for this scenario maintain the flammable vapour cloud from a leakage mostly within the site boundary. The probability of ignition is therefore low. However, in the event of ignition, the radiation flux on the store to the west is unacceptable. Possible actions include: •

Reduce probability of leakage as per Scenario 2.

•

Install improved fire-fighting/fire protection and gas detection/gas dispersion facilities.

•

Construct fire wall on store wall adjacent to loading point.

•

Install water curtain on store wall.

4.3.15 Scenario 15 : Leak from incorrect or damaged coupling at bulk road vehicle loading point Assume equivalent hole diameter = 25 mm Adopt L/D = 0 M = 0.6A

2ρ (Po − Pa ) 5

As for Scenario 13 choose Po = 9 x 10 N/m

π x 0.025 2 M = 0.6 x 4

2

2 x 510 (9 − 105 − 1 x 105 )

= 8.4 kg/sec From Figure 3 estimated distances to LFL are 5D conditions - 45 m 2F conditions - 85 m From Figures 4 to 16 distances to radiation flux levels from liquid fires are: Horizontal Jet Fires

Vertical Jet Fires

1.5

kW/m²

110 m

95 m

5

kW/m²

80 m

60 m

8

kW/m²

75 m

50 m

13 KW/m²

70 m

40 m

44

60m

20 m

kW/m²

The distances to LFL for this scenario extend well beyond the site boundary. The probability of ignition of leakage is quite high. The radiation flux levels exceed allowable limits at the site boundaries and at buildings within the depot. Possible actions: •

Remote-operated emergency shutdown system as per Scenario 13.

•

Fusible links in emergency shutdown system.

•

Regular training of drivers to ensure correct operating procedures.

•

Improved fire-fighting/fire protection and gas detection/ gas dispersion.

5.

REFERENCES (1)

Discharge Rate Calculation Methods For Use In Plant Safety Assessments. P.K. Ramskill, UKAEA Safety and Reliability Directorate. Report SRD R352, February 1986.

(2)

API Recommended Practice 520. Recommended Practice for the Design of Pressure-Relieving Systems in Refineries. Part I - Design.

(3)

API Recommended Practice 521, Guide For Pressure Relief and Depressuring Systems.

(4)

Loss Prevention In The Process Industries, Frank P. Lees Chapter 15. Butterworths 1980.

TABLE 1(A) :

DISCHARGE AREAS FOR ‘REGO’ PRESSURE RELIEF VALVES

Relief Valve Part No/Series

2

Orifice dia (D) (in)

Discharge Area 2 (A) (in )

Discharge Area (m ) (A) (x 10-4)

A8434 GN A8436 GN A8534 FGN

1.015 1.766 1.015

0.809 2.449 0.809

5.22 15.80 5.22

7534 B 7583 G 8684 G 8685 G 7534 G

1.843 0.795 0.921 1.218 1.843

2.668 0.496 0.666 1.165 2.668

17.21 3.20 4.30 7.52 17.21

A3149 L050 3149 L200 3127 G 3129 G 3131 G

1.641 1.641 0.274 0.386 0.736

2.115 2.115 0.059 0.117 0.425

13.64 13.64 0.38 0.75 2.74

W3132 G 3132 G T3132 G MV3132 G 3135 G

0.937 1.032 1.032 1.032 1.156

0.689 0.836 0.836 0.836 1.049

4.44 5.39 5.39 5.39 6.77

AA3135 UA 250 3133 G A3149 G AA3135 UA 265 3127 K 3129 K

1.156 1.218 1.641 1.156 0.274 0.386

1.049 1.165 2.115 1.049 0.059 0.117

6.77 7.52 13.64 6.77 0.38 0.75

TABLE 1(B) :

Relief Valve Part No/Series

H 280 SERIES H 5110 SERIES H 110 SERIES H 135-250 H 160 SERIES H 185 SERIES H 148 H 173 H 225 SERIES H 250 SERIES H 275 SERIES H 365 SERIES H 385 SERIES

DISCHARGE AREAS FOR ‘FISHER’ PRESSURE RELIEF VALVES

2

Orifice dia (D) (in)

Discharge Area 2 (A) (in )

Discharge Area (m ) (A) (x 10-4)

1.844 1.844 0.283 0.390 0.390 0.742 0.390 0.390 0.784 1.006 1.230 0.523 0.581

2.67 2.67 0.06 0.12 0.12 0.43 0.12 0.12 0.48 0.79 1.19 0.21 0.26

17.23 17.23 0.39 0.78 0.78 2.77 0.78 0.78 3.10 5.10 7.68 1.35 1.68

TABLE 1 (C) :

DISCHARGE AREAS FOR OTHER PRESSURE RELIEF VALVES

( As used on Manufacturing sites )

2

2

Discharge Area (in ) (A)

Inlet/Orifice/Outlet

Discharge Area (m ) (A) (x 10-4)

0.71 1.26 1.98 5.05 11.86 18.41 41.16 71.23 103.23 167.75

0.110 0.196 0.307 0.785 1.838 2.853 6.380 11.040 16.000 26.000

1D2 1E2 1½F2 2H3 3K4 4L6 4P6 6Q8 6R10 8T10

TABLE 2 :

RELIEF VALVE FIRE & RADIATION FLUX DATA FOR PROPANE

Mass Flow

Stack Dia.

Stack Output Height

Stack Length

Flame Length

Flame Lift

kg/s

ins

m

m

m

m

Distance downwind Tank Top Level Radiation Flux 8 kW/m

32 2

kW/m

Ground Level Radiation Flux 44

2

kW/m

1.5 2

kW/m

5 2

kW/m

8 2

kW/m

13 2

kW/m2

2.5

1.25

1.65

0.2

10.3

1.8

12

-

-

30

15.5

10.5

6

5.0

1.77

4.6

2.0

13.9

2.5

15

-

-

40

19

11

-

7.5

3.0

4.6

2.0

17.1

3.1

19.5

-

-

50

25.5

16.5

-

10.0

6.0

15.4

2.0

17.1

3.8

26.5

-

-

60

10.5

-

-

15.0

6.0

9.0

2.0

24.2

4.3

30

-

-

73

35.5

21.5

-

20.0

8.0

21.0

2.0

28.0

5.0

36.5

-

-

82

23

-

-

25.0

8.0

23.0

2.0

30.3

5.4

39.5

-

-

89

-

-

-

30.0

8.0

23.0

2.0

32.4

5.8

42.5

-

-

95

31

-

-

40.0

8.0

23.0

2.0

36.1

6.4

47.5

-

-

109

42

-

-

Notes : 1. 2. 3. 4.

For layout see Figure 1 All calculations for windspeed 5 m/s Mass flows of 2.5, 5.0, 7.5 and 15 kg/s refer to propane in bullets. Mass flows of 10, 20 kg/s, and greater refer to propane in spheres.

TABLE 3 :

RELIEF VALVE FIRE & RADIATION FLUX DATA FOR BUTANE

Mass Flow

Stack Stack Flame Flame Output Length Length Lift Height Off

kg/s

Stack Dia.

ins

m

m

m

m

Distance downwind (m)

8 kW/m

2.5 5.0 7.5 10.0 15.0 20.0 25.0 30.0

1.25 1.77 3.0 6.0 8.0 10.0 10.0 10.0

Notes : 1. 2. 3. 4.

1.65 4.6 4.6 9.0 21.0 23.0 23.0 23.0

0.2 2.0 2.0 2.0 2.0 2.0 2.0 2.0

10.6 14.4 17.7 21.9 26.7 33.2 32.9 34.8

1.9 2.6 3.2 3.9 4.8 3.0 5.9 6.2

Tank Top Level Radiation Flux 32 44 1.5

12.5 16 21.5 28 35.5 44 45 48

2

kW/m

6 -

2

kW/m

-

2

kW/m

Ground level Radiation Flux 5 8 13 2

30 42 52 65 77 93 98 105

For layout see Figure 1 All calculations for windspeed 5 m/s Mass flows of up to 10 kg/s refer to butane in bullets. Mass flows of 15 kg/s, and greater refer to butane in spheres.

2

kW/m

16 20 27 32 23 38 39 43

kW/m

2

11.5 12 18 19 -

2

kW/m

6.5 -

FIGURE 1 :

SCHEMATIC OF MODEL FACILITIES (at windspeed 5m/s)

FIGURE 2 :

EXAMPLE PLUMEPATH DISPERSION PROFILE FOR BUTANE

FIGURE 3 :

DISPERSION DISTANCE TO LFL FOR HORIZONTAL PROPANE & BUTANE RELEASES

WEATHER 2F = WIND SPEED 2 m/s. WEATHER STABILITY F WEATHER 5D = WIND SPEED 5 m/s. WEATHER STABILITY D SURFACE ROUGHNESS = 0.1 m

FIGURE 4 :

DISTANCE TO 1.5 Kw/M2 RADIATON FLUX FOR VAPOUR AND LIQUID HORIZONTAL BUTANE JET FIRES

FIGURE 5 :

DISTANCE TO 5 Kw/m2 RADIATON FLUX FOR VAPOUR AND LIQUID HORIZONTAL BUTANE JET FIRES

FIGURE 6 :

DISTANCE TO 8 Kw/m2 RADIATON FLUX FOR VAPOUR AND LIQUID HORIZONTAL BUTANE JET FIRES

FIGURE 7 :

DISTANCE TO 13 Kw/m2 RADIATON FLUX FOR VAPOUR AND LIQUID HORIZONTAL BUTANE JET FIRES

FIGURE 8 :

DISTANCE TO 32 Kw/m2 RADIATON FLUX FOR VAPOUR AND LIQUID HORIZONTAL BUTANE JET FIRES

FIGURE 9 :

DISTANCE TO 44 Kw/m2 RADIATON FLUX FOR VAPOUR AND LIQUID HORIZONTAL BUTANE JET FIRES

FIGURE 10 :

FLAME LENGTHS FOR HORIZONTAL BUTANE JET FIRES

FIGURE 11 :

DISTANCE TO 1.5 Kw/m2 RADIATON FLUX FOR VAPOUR AND LIQUID VERTICAL BUTANE JET FIRES

FIGURE 12 :

DISTANCE TO 5 Kw/m2 RADIATON FLUX FOR VAPOUR AND LIQUID VERTICAL BUTANE JET FIRES

FIGURE 13 :

DISTANCE TO 8 Kw/m2 RADIATON FLUX FOR VAPOUR AND LIQUID VERTICAL BUTANE JET FIRES

FIGURE 14 :

DISTANCE TO 13 Kw/m2 RADIATON FLUX FOR VAPOUR AND LIQUID VERTICAL BUTANE JET FIRES

FIGURE 15 :

DISTANCE TO 32 Kw/m2 RADIATON FLUX FOR VAPOUR AND LIQUID VERTICAL BUTANE JET FIRES

FIGURE 16 :

DISTANCE TO 44 Kw/m2 RADIATON FLUX FOR VAPOUR AND LIQUID VERTICAL BUTANE JET FIRES

FIGURE 17 :

LPG DEPOT LAYOUT – WORKED EXAMPLE

FIGURE 18 :

FLOWSCHEME – WORKED EXAMPLE

FIGURE 19 :

NOZZLE DETAILS OF PROPANE SPHERE – WORKED EXAMPLE

FIGURE 20 :

NOZZLE DETAILS OF BUTANE SPHERE – WORKED EXAMPLE