ISO/DIS 22899-2:2026(en)

ISO TC 92/SC 2

Secretariat: ANSI

Date: 2025-11-20

Determination of the resistance to jet fires of passive fire protection materials — Part 2: Guidance on test method selection and implementation methods

© ISO 2026

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Contents

Foreword iv

1 Scope 1

2 Normative references 1

3 Terms and definitions 1

4 Symbols and abbreviated terms 2

5 Principle 2

6 Selection of applicable test methodology 3

6.1 Methodology 3

6.2 Test method selection factors 3

6.2.1 Partial confinement scenarios 3

6.2.2 Natural gas fuelled jet fires 3

6.2.3 Hydrogen jet fires 3

6.2.4 Flashing liquid jet fires 4

6.2.5 Live crude or crude/NG mix jet fires 4

6.2.6 Other jet fires 4

7 Classification (optional) 4

7.1 General 4

7.2 Type of fire 4

7.3 Type of application 4

7.4 Initial Substrate temperature 5

7.5 Maximum temperature 5

7.6 Maximum temperature rise 5

7.7 Period of resistance 5

7.8 Integrity 6

8 Applicability of test results 6

9 Combination of results from hydrocarbon furnace and resistance to jet fire tests 6

9.1 General 6

9.2 Hydrocarbon and jet fire resistance tests 6

9.3 Erosion factor 7

9.4 Thickness of fire protection material 8

9.5 Section factor 8

9.6 Assessment methodology: structural sections 8

9.7 Assessment methodology: extension testing for HHF 9

9.7.1 Full characterisation 10

9.7.2 Simplified method 10

9.8 Assessment methodology: divisions 10

9.9 Assessment methodology: load bearing divisions 11

Bibliography 11

Foreword

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This document was prepared by Technical Committee ISO/TC 92, Fire Safety, Subcommittee SC 2, Fire Containment.

A list of all parts in the ISO 22899 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Determination of the resistance to jet fires of passive fire protection materials — Part 2: Guidance on test method selection and implementation methods

The tests specified in ISO 22899-1 and ISO 22899-3 are designed to give an indication of how passive fire protection materials and systems will perform in a jet fire. This part of ISO 22899 provides:

— guidance on the selection of applicable method of test;

— guidance on the combination of results from hydrocarbon tests and resistance to jet fire tests.

ISO 22899-1 and ISO 22899-3 tests report the thickness of fire protection material or system (sometimes referred to as passive fire protection; PFP) required to resist the application of a ‘jet fire’.

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 22899‑1, Determination of the resistance to jet fires of passive fire protection materials — Part 1: General requirements

ISO 22899‑3, Determination of the resistance to jet fires of passive fire protection materials — Part 3: Extended test requirements

PFPNet 23-007 Guidance on Selecting the Appropriate Jet Fire Resistance Test for Passive Fire Protection Systems

For the purposes of this document, the terms and definitions given in ISO 22899‑1 and the following apply.

3.1

critical temperature

maximum temperature that the equipment, assembly or structure to be protected may be allowed to reach

3.2

critical time

minimum time required to reach the critical temperature

3.3

erosion factor

extra thickness of passive fire protection required when comparing the results from a jet fire test with those from a different type of hydrocarbon test on specimens with a similar section factor (e.g. 100 m⁻¹) and period of fire resistance, the critical temperature or critical time or both

3.4

integrity

ability of a fire barrier to prevent the transmission of flame, smoke, hot and toxic gases

3.5

section factor

ratio of the area per unit length of steel exposed to fire divided by the volume per unit length of the section

Note 1 to entry: The lower the section factor, the slower the rate of heat increase for a given volume of steel. See 9.5 for a more detailed explanation.

The objective of the jet fire test is to establish the amount of passive fire protection (PFP) material that needs to be applied to a structural member, valve, penetration sealing system, etc., in order to resist exposure to a jet of ignited fuel. The practicalities of jet fire testing prohibits characterisation of PFP materials in detail and therefore it is practical to determine the amount of PFP above and beyond that needed to satisfy the criteria of a hydrocarbon fire resistance test. This additional thickness of material, known as the erosion factor, is determined once for each similar element or construction, which may be added to the thickness of material determined for a similar range of such elements, when evaluated for fire resistance against hydrocarbon fire resistance tests using the principles provided below.

The method provides an indication of how passive fire protection materials perform in a jet fire that may occur, for example, in petrochemical installations where ignitable gases are stored at pressure. It aims to simulate the thermal and mechanical loads imparted to passive fire protection material by large-scale jet fires resulting from high-pressure releases of flammable gas, pressure liquefied gas or flashing liquid fuels. Jet fires give rise to high convective and radiative heat fluxes as well as high erosive forces. To generate both types of heat flux in sufficient quantity, a 0,3 kg s⁻¹ sonic release of gas is aimed into a shallow chamber (ISO 22899-1) or an extended compartment (ISO 22899-3), producing a fireball with an extended tail. The flame thickness is thereby increased and hence so is the heat radiated to the test specimen. Propane is used as the fuel since it has a greater propensity to form soot than does natural gas and can therefore produce a flame of higher luminosity. High erosive forces are generated by release of the sonic velocity gas jet 1 m from specimen surface. The jet velocity is ca. 100 ms⁻¹ at 0,25 m from the back of the flame recirculation chamber (e.g. the front of the web of a structural-steel specimen) and ca. 60 ms⁻¹ at the back of the chamber. The average heat flux under ISO 22899-1 conditions is approximately 240 kW m⁻² and the maximum heat flux 300 kW m−2.^[1] The heat fluxes are highest in the mid-to-upper part of the chamber and lowest in the corners and at the jet impact zone. The combination of fuel, release rate and experimental arrangement is intended to apply a similar heat loading to the specimens as would be given by a 3 kg s⁻¹ natural gas (60 bar, 20 mm orifice) jet fire released 9 m (the distance for the most severe combination of erosive forces and heat transfer) from a target (see Clause 6). The average heat flux under ISO 22899-3 conditions is described therein as approximately 350 kW m^-2, and is intended to apply a similar heat loading to the specimen as would be given by a 20 kg s^-1 natural gas release,^[21] or a specimen exposed to severe heating in a ventilation-controlled compartment jet fire^[14].

The following is a guide to the methodology of testing PFP systems with the applicable jet fire resistance test method. It is adapted and summarised, with permission, from normative reference 3. Technical justification for the methodology is given in normative reference 3 Appendix II.

The following steps should be taken when selecting an appropriate jet fire test:

Step 0   Comply with National Regulation or Company Guidelines if their rules require PFP to resist a specified heat flux. For example, if resistance to a thermal load of 350 kW/m2 is the required by law or Company policy then a HHF test in accordance with ISO 22899-3 is necessary. If National Regulations or Company Guidelines do not exist, then proceed to Step 1.

Step 1   Identify a loss of containment scenario from a risk or hazard analysis of the industrial plant.

Step 2   For the chosen scenario, identify the mass flow rate, impingement distance, and degree of ventilation (when the release is into a potentially confined area).

Step 3   Refer to the relevant section of 6.2.

Step 4   Refer to normative reference 3, as required, for more detail.

Determine whether the combustion is fuel-controlled or ventilation-controlled. High heat fluxes have not been observed in ventilation-controlled conditions, however extremely high heat fluxes have been observed in several fuel-controlled tests. Normative reference 3 includes information on how to determine whether a fire should be considered fuel-controlled or ventilation-controlled.

ISO 22899-3 is appropriate for fuel-controlled scenarios. For ventilation-controlled scenarios ISO 22899-1 or -3 may be applicable depending on the fuel type. Refer to sections 6.2.2-6.2.6.

Natural gas jet fires, including natural gas jet fires up to 24 % by volume hydrogen, of mass flow rates above 4 kg/s will have a region of the flame in which a target will be subject to high heat fluxes. ISO 22899-1 or ISO 22899-3 may be applicable depending on the mass release rate and the impingement distance.

Hydrogen jet fires have convective heat fluxes that can exceed 700 kW/m², and therefore ISO 22899-1 and ISO 22899-3 are not applicable. See 6.2.6.

ISO 22899-1 is applicable to releases of LPG. For mixtures of LPG and natural gas refer to 6.2.2.

Crude oil jet fires, including mixtures of crude and natural gas, of mass flow rates above 3 kg/s will have a region of the flame in which a target will be subject to high heat fluxes. ISO 22899-1 or ISO 22899-3 may be applicable depending on the mass release rate and the impingement distance.

Other jet fires are outside the scope of this standard as insufficient evidence is available at the time of publication for general conclusions to be drawn. Seek expert advice on whether further information has become available. In the absence of further guidance, specific testing is recommended.

The classification is related to the type of application and based on the critical temperature and the period of exposure to the jet fire. The procedure used is based on that proposed in ISO 13702. The classification rating is specified as:

Type of fire/Type of application/Critical temperature (degrees centigrade)/Period of resistance (minutes)

It must be noted that critical temperature is specific to the application or item being protected, and is independent of the protection system. The critical temperature is defined according to the performance criteria for the equipment, assembly or structure being protected. For example, 140 °C is typically used for fire barriers and 400 °C is typically used for load-bearing steel structures. The corresponding value for load-bearing aluminium structures is typically 200 °C. Defining the ability of a protection system to meet the critical temperature requirement requires knowledge of the average initial substrate temperature and the maximum temperature rise, as described in 7.4 and 7.6.

ISO 13702 distinguishes between “standard fires” (cellulosic fires – referred to in the standard) (CF), hydrocarbon pool fires (HC) and jet fires (JF). Following publication of ISO 22899-3 the high heat flux jet fire (HHF) shall also be used. As suggested in ISO 13702, the letters JF or HHF represent the type of fire used in this test. The other designations are mentioned as it is likely that some fire scenarios may be specified in the form of a jet fire followed by a hydrocarbon pool fire. In practice, it is not easy to perform combined jet fire and furnace tests on the same specimen and hence a method of combining the results is required (see Clause 9). In such cases, the type of fire and its duration should be specified. Hence, for a fire barrier designed to withstand a 15 minute jet fire followed by a 30 minute hydrocarbon pool fire with a critical temperature of 140 °C, the rating would be:

(JF+HC) / Type of application (for example, Fire barrier) / 140 °C / (15_JF + 30_HC)

For structural steelwork designed to withstand a 5 minute high heat flux jet fire following by a 10 minute standard jet fire, followed by 20 minutes hydrocarbon pool fire with a critical temperature of 400 °C, the rating would be:

(HHF+JF+HC) / Structural steelwork / 400 °C / (5_HHF + 10_JF + 20_HC)

The specimen tested will depend on the practical application being considered. The most common types of application are:

— structural steel;

— pressure vessels;

— critical process control equipment;

— pipes;

— safety critical control units;

— fire barriers (for example, divisions, walls, floors, bulkheads, decks, etc.);

— cable transit systems; and

— pipe penetration seals.

The application should be specified in the form indicated above. Where the test is used for another other type of application (e.g. control panel, emergency shut down valve, inspection hatch), this should be specified in a similar way.

The substrate / specimen thermocouple temperature immediately before the start of the test. The initial temperature shall be taken as the temperature measured by the thermocouple that recorded failure, except for specimens subject to a conditioning procedure intended to stabilise the specimen at ambient temperature, in which case it is acceptable to use the average initial substrate temperature.

The maximum temperature recorded during the test.

The maximum temperature rise is the highest temperature rise observed at any location during the test.

The period of resistance is the total time that the specimen is exposed to the jet fire. This is the overall test duration less any time that the jet is interrupted as described in ISO 22899-1:2021 Clause 14.3.2.

In deriving the rating, it is necessary to take into account the practical requirement to measure the time to achieve a given maximum temperature rise (T_rise), the initial substrate temperature (T_initial), and the critical temperature (T_critical).

First, the permitted maximum temperature rise must be calculated as:

T_rise = T_critical – T_initial

Two examples are given of the application of the classification procedure to the protection of structural steel and to a valve.

Case 1 Structural steel is required to maintain a temperature of 400 or below after 60 minutes of jet fire exposure. Hence the rating is:

JF/Structural steel/400 °C/60.

The average initial substrate temperature is measured as 20 °C, therefore the permitted maximum temperature rise is 380 °C.

The protection system shall be designed and specified accordingly, based on a test or tests to this standard that demonstrated a maximum temperature rise not exceeding 380 °C after 60 minutes.

Case 2 A valve is required to maintain a temperature of 150 °C or below after 15 minutes of jet-fire exposure:

The valve’s normal operating temperature is 80 °C, therefore the maximum permitted temperature rise is 70 °C.

The protection system shall be designed and specified accordingly, based on a test or tests to this standard that demonstrated a maximum temperature rise not exceeding 70 °C after 15 minutes.

For fire protection materials and systems with joints (e.g. transit systems, fire barriers), it is important that the transmission of flame, smoke, hot and toxic gases be prevented, i.e. that their integrity is maintained. If integrity requirements are part of the classification procedure, as in all cases for systems with joints, it is recommended that additional thermocouples are placed behind the joints to determine if there are any sudden increases in temperature indicative of breakthrough of flames or hot gases and smoke. When practicable, provision should be made for video recording the rear of any joints. Other techniques, such as thermal imaging, may also be used. If it is necessary to measure the concentration of toxic gases produced, the rear of the environmental chamber can be sealed and the gases produced extracted at a known rate past concentration sensors.

Tests in accordance with ISO 22899-3 are more onerous than tests in accordance with ISO 22899-1 and may be used in an assessment of PFP material performance under ISO 22899-1 jet fire conditions. The reverse is not true, i.e., ISO 22899-1 test results cannot be used in an assessment of PFP material under ISO 22899-3 high heat flux conditions.

The jet fire test methods are complementary to hydrocarbon fire resistance testing and the results from both types of test should be taken into account when assessing the effectiveness of PFP materials. Jet fire tests can be considered more onerous than hydrocarbon fire resistance testing, however the difference in test configurations can lead to differences in heat loss from specimens. The heat loss from the jet fire test specimen should be matched as closely as practically possible with respect to the reference hydrocarbon fire resistance test.

Jet fire tests in accordance ISO 22899-3 shall be considered more onerous than those in accordance with ISO 22899-1. Tests in accordance with ISO 22899-1 shall be assessed and classified as standard jet fire (JF) results. Tests in accordance with ISO 22899-3 shall be classified as high heat flux (HHF) results

Although protection against a “standard” fire (e.g. from timber, paper or cotton), has historically dominated the commercial and industrial fire scenes, it is not very representative of a fire on a process plant involving spilled or pressure released hydrocarbons. This is because a fire involving cellulosic materials grows relatively slowly compared to a hydrocarbon fire. Various national and international fire tests of fire protection products exist, which are based on hydrocarbon fires. These are mainly furnace tests which expose a sample to a pre-determined heat-up regime while monitoring the thermal response of the test specimen. Common standards for furnace testing are UL1709, ISO 834, or EN 1363-1 (the latter two both using a hydrocarbon time-temperature curve, such as that defined in ISO 834 or EN 1363-2). A standard fire test provides a reproducible time/temperature heating regime within which the response of test specimens can be assessed against various criteria. While hydrocarbon furnace tests are designed to represent a particular type of fire, they do not reproduce the actual fire conditions. The furnace temperature and total heat flux may be similar to those generated within a fire but parameters such as

— the balance between radiative and convective heat transfer,

— pressure fluctuations due to turbulence,

— erosive forces from high gas velocities,

— thermal shock, and

— differential heating

are not reproduced. In a jet fire, the fire protection products will be subjected to erosive forces, pressure fluctuations and higher heat fluxes. It should be noted that the highest erosive forces are not in the region of highest heat flux. Hence, the results of both tests should be considered together when assessing the performance of a fire protection product or material in a range of scenarios. However, in combining results, it is not valid to compare mean substrate temperature from a hydrocarbon fire resistance test with a mean substrate temperature from a jet fire because of the non-uniformity of the heating in the jet fire test.

For many types of protected item, such as steelwork, it is not practicable to test all the practical combinations of substrate thickness, section factor, duration, etc. required, and hence methods are required to predict the thickness of fire protection product or material required.

The concept of erosion factor was introduced as a means of providing an additional thickness of PFP, in addition to that required for hydrocarbon fire resistance, necessary to protect against jet fire.

The erosion factor shall be determined for each combination of temperature and duration at which classification is required. It is calculated as:

t_e = t_jf – t_pf

where

t_e is the erosion thickness (mm)

t_jf is the jet fire total thickness (mm) required to limit the substrate temperature rise to a specific value for a specific duration.

t_pf is the pool fire assessment thickness (mm) at the equivalent temperature, duration and section factor as the t_jf.

Historically, jet fire testing has reported times to a given temperature rise while hydrocarbon resistance testing has reported times to a given absolute temperature. This discrepancy introduces a minor optimism into the methodology.

Use of the methodology herein for substrate that are not at ambient temperature at the onset of fire (20 °C +/- 20 °C) should calculate a modified acceptable temperature as the basis of product specification. This includes PFP for process equipment or storage vessels at elevated temperature or cryogenic temperatures.

EXAMPLE:  

A valve with an operating temperature of 80 °C must be protected from reaching a temperature of 200 °C within 15 minutes.

Permitted temperature rise = 200-80 = 120 °C.

The most common methods used to provide data applicable to a range of situations are the graphical and regression methods, examples of which are described in ISO 834-11. For structural steel elements, these are based on the performance of a series of furnace tests conducted on structural elements with varying section factors, usually between 50 m⁻¹ and 350 m⁻¹, to various fire durations (t_resistance) and limiting temperatures. The thickness of material (w, mm) required to provide specific standards of fire resistance are derived by means of assessment from furnace tests chosen to cover the range of section factors, thicknesses and durations required. The assessment method used shall be consistent across the dataset for each test specimen configuration. Generally, interpolation of fire test data is allowed but extrapolation is not. The results are usually presented in tabular form by the manufacturers or certification bodies.

The methodology of calculation of PFP thickness required for hydrocarbon fire resistance is not important, however the resulting erosion thicknesses are specific fire test standard and the assessment report number must be clearly stated as on any resulting certification or assessment report because jet fire erosion thicknesses are specific to the hydrocarbon resistance data used and are not applicable to any other fire test standard or assessment.

In principle, the ability of a substrate to absorb heat is generally determined by its section factor (S_f, m⁻¹) or A/V ratio (also known as H_p/A), i.e. the heated area per unit length (A, m²) divided by the volume per unit length (V, m³). Historically^[16], the section factor has been defined in terms of the heated perimeter and area of cross-section but recent standards have used the revised definition given above. However, the units are the same. A substrate with a large mass and small surface area will take a longer time to reach critical temperature than one with a small mass and large surface area. Hence, in furnace tests, it is usual to vary the duration, section factor and fire protection product thickness in order to provide an estimate of the thickness required in a range of situations. Testing of unique items should use a representative or conservative section factor value. For the use of steelwork protection the appropriateness, or otherwise, of using the section factor has not been established for jet fire testing and, currently, it is common practice to jet fire test a single section factor value on the basis that variations in section factor are considered within the hydrocarbon furnace assessment, and thus in the total jet fire thickness, when combined with the erosion factor concept herein.

A pool fire assessment based on a published HC test standard is a prerequisite for a jet fire assessment using the methodology herein. The scope of the HC listing or assessment report shall form the maximum possible scope of jet fire assessment. No extrapolation is permitted based on jet fire test data.

All jet fire tests shall be compliant with ISO 22899-1 or ISO 22899-3 and should be conducted by a lab accredited to ISO 17025. The number of tests and the maximum permitted interpolation shall be decided by the assessment or classification authority. Tests shall include the minimum thickness, maximum thickness and, if applicable, reasonably spaced intermediate thicknesses. Additional tests are permitted.

The structural steelwork test specimen, representative of open section (such as I-sections), and tubular section test specimens, representative of hollow sections, shall be treated separately. Where jet fire protection is required for both I sections and hollow sections, evaluation may take place for the geometry with the most onerous erosion factor, determined at all limiting temperature of interest at an intermediate thickness, and for ISO 22899-1 and ISO 22899-3 separately.

Tabulate the times to each temperature rise for all tests. Note the failure criteria in ISO 22899-1 (temperature rise, single point of failure) shall be complied with. See example in table 1.

Table 1

For each critical temperature value independently calculate the predicted total jet fire DFT required to prevent failure for each duration of interest using one of the methods given in Annex A. Tabulate the total jet fire thicknesses as given in Table 2. The maximum and minimum thickness limits should be set by the authority having jurisdiction or the body issuing the classification or certification. In the absence of such limits 5 % should be used. Predicted thicknesses that exceed the maximum limit are not permitted. The total jet fire thickness shall not decrease with increasing duration.

Table 2

The erosion factor shall be determined for each combination of temperature and duration at which classification is required in accordance with 9.3. Erosion factors shall be tabulated in the same format as Table 2.

NOTE: Erosion thickness for jet fire should not decrease with increasing duration. This possibility exists due to the non-linear and diverging nature of the two test methods being compared, however jet fires are evidently more onerous with increasing duration and therefore correction should be applied. Where a value tabulated in the format above is lower than the value above it, it should be replaced by that value.

High thickness tests may terminate before the higher temperatures stated in the assessment. It is acceptable to use the test termination time for all limiting temperatures in the assessment including those higher than the maximum temperature rise reached.

NOTE: the above method is only directly applicable to tests in which the system thickness is the only variable changed. Further changes (e.g. joint methods, reinforcement, insulation grade etc.) shall be considered at the discretion of the certifying authority. Any assessment shall include an assessment of integrity for assemblies and systems.

The assessment shall clearly state whether it is applicable to standard jet fires (based on testing to ISO 22899-1 or a mixture of tests to ISO 22899-1 and ISO 22899-3) or to high heat flux jet fires (based on test to ISO 22899-3 only).

PFP materials with an assessment for standard jet fire can calculate a further HHF erosion thickness to be added on to product thickness requirement for combination scenarios. For example, a 5 minute high heat flux jet fire following by a 10 minute standard jet fire, followed by 45 minutes hydrocarbon pool fire, the rating would be:

Required PFP thickness = hydrocarbon DFT for 60 minutes + JF erosion thickness for 15 minutes + HHF erosion thickness for 5 minutes.

Two methods are available to characterise the required HHF erosion factors: a full characterisation or a simplified method.

The methodology described in 9.6 shall be undertaken in full except that the HHF erosion thicknesses shall be calculated as follows:

t_e-hhf = t_hhf – t_jf

where

t_e-hhf is the high heat flux erosion thickness (mm)

t_hff is the high heat flux total jet fire thickness (mm) required to limit the substrate temperature rise to a specific value for a specific duration

t_jf is the jet fire total thickness (mm) required to limit the substrate temperature rise to a specific value for a specific duration.

The high heat flux erosion thickness calculation method shown above assumes a 22889-1 assessment has been undertaken, and that the assessment must be suitable for combination jet fire scenarios, i.e. those when the high heat flux component has a shorter duration than the standard jet fire component.

It is also acceptable to calculate a high heat flux erosion thickness directly on the basis of hydrocarbon fire resistance data, as follows:

t_e-hhf = t_hhf – t_hc

where t_hc is the hydrocarbon fire resistance thickness (mm)

The full characterisation method for extension testing must be based on a HHF erosion thickness to be added to the total 22899-1 jet fire thickness, as shown in Figure 1. It is not acceptable to calculate the example shown in Figure 1 on the basis of a 5 minute erosion thickness for HHF

Figure 1 — Combination scenario thickness calculation for a 60 minute total fire duration, of which 15 minutes is jet fire, of which the first 10 minutes is HHF

It is not acceptable to use the methodology illustrated in Figure 2 for the scenario shown in Figure 1, because erosion thicknesses must be calculated based on the difference in performance from the start of the fire (not 10 minutes into the fire, as happens in Figure 2).

Figure 2 — Incorrect methodology for calculating extension testing HHF thicknesses for a 60 minute total fire duration,
of which 15 minutes is jet fire, of which the first 10 minutes is HHF

A HHF test shall be undertaken using the maximum DFT and minimum DFT tested to ISO 22899-1. The DFTs of the HHF specimen shall be within 10 % of those previously tested, and the test results may be linearly corrected for deviations in thickness. If the worst case of maximum and minimum DFT can be clearly established, it is acceptable to test only the worst case DFT. The determination of the worst case, and the use of the simplified method in general, is at the discretion of the authority having jurisdiction or the certification body. The time to each critical temperature of interest shall be compared, and a modification factor to give the high heat flux total jet fire thickness shall be determined as:

Modification factor (f_hhf)= time to critical temperature JF / time to critical temperature HHF.

The worst case modification factor shall be used, and the modification factor shall be at least 1. The high heat flux erosion thickness shall be calculated as:

t_e-hhf = ( f_{hhf *} t_jf ) – t_jf

Representative scale divisional specimens shall be minimum 2,48 m x 2,42 m, in accordance with ISO 20902-1. The tests shall be conducted in accordance with ISO 22899-3, with the specimen replacing the rear compartment wall.

Representative division tests can be directly classified in accordance with section 7.

Erosion thicknesses for divisions can also be calculated using the methodology given in 9.7.1. The hydrocarbon fire resistance test data shall be based on ISO 20902-1 and the specimen construction and non-fire side insulation shall be representative of tests undertaken in accordance with ISO 20902-1.

Reduced scale testing can be undertaken for products that have been tested and assessed in accordance with ISO 20902-1.

Reduced scale tests shall be based on the ISO 22899-1 panel test specimen or the ISO 22899-1 structural steel test specimen without the central web. Divisions shall not be assessed from this reduced scale jet fire test method alone, as the structural steel test specimen and other reduced scale specimens cannot recreate the deflections present on a larger scale and may not capture the mechanism of failure of the PFP system.

The panel test specimen shall be designed so that the rate of heat loss from the non-fire exposed surface matches that in the hydrocarbon fire resistance test as closely as possible, ignoring differences in ambient temperature.

NOTE: in practice this means using the same materials, insulation, surface finish, etc.

Reduced scale jet fire tests may be undertaken in accordance with either ISO 22899-1 or ISO 22899-3.

The JF data shall be assessed to determine the time to a point rise of 180 °C or the time to an average rise of 140 °C, whichever occurs first.

Erosion thicknesses shall be calculated as:

t_e-div=t_jf-div - t_hc(180)

where

t_e-div is the erosion thickness for divisions at a given duration

t_jf-div is the required DFT for the given duration (or t_hhf-div may be used if the testing is based on ISO 22899-3)

t_hc(180) is the required DFT from the HC structural assessment (I-sections) at 180 °C for the given duration

Divisions with a requirement to maintain structural stability, such as H0-400 divisions, shall undergo a further assessment in addition to that in 9.8 or 9.9. The erosion thickness required to maintain the temperature of the test specimen below the critical temperature shall be assessed at the equivalent duration, section factor, and temperature. The higher of this erosion thickness and that calculated in 9.8 or 9.9 shall be the required thickness, unless the division is constructed of a material which will provide the necessary integrity for the required duration (such as steel), in which case only the H0-400 erosion thickness shall be used.

EXAMPLE:  

A H0-400 division has a structural stability requirement for 120 minutes.

There is no insulation requirement and the minimum DFT tested of 3 mm maintained integrity for 2 hours.

However, if the total JF thickness required to limit the temperature rise to 400 °C for 2 hours is calculated to be 10 mm and the HC assessed thickness for the same section factor, critical temperature and duration is 6 mm, then the erosion thickness is 4 mm.

The final JF thickness is this value or the higher of the two values (depending on the nature of the division), hence 4 mm.

CPCE should be tested in accordance with ISO 22899-3 on a representative scale. The ISO 22899-1 test configurations

Jet fire testing shall be undertaken to ISO 22899-1 or ISO 22899-3 except where modified by the provisions below.

ISO 22899-1 jet fire test is intended as a PFP product test, not a test of a particular item of equipment, is therefore compatible with classification by insulation rating only, linked to a given time period and stated temperature rise. The ISO 22899-3 jet fire test is compatible with classification based on operability, via functional testing, and classification by insulation rating.

Classification by insulation rating with ISO 22899-1 may be performed using the following test specimen:

a) A tubular test specimen, for applicability to items mounted on pipes and of similar geometry/configuration to the tested specimen, or;

b) A planar specimen with a protruding box of side length 260 mm +/- 10 mm, protruding for 250 mm +/- 10 mm, constructed from the same plate thickness as the surrounding panel or from a frame representative of the intended use attached to the panel (as shown in Figure 6). The protruding box shall have a distance to the vertical centre-line (A) of 100 mm to 200 mm, and a distance to the inner-edge of the recirculation chamber at the bottom of 230 mm to 620 mm.

NOTE: The ISO 22899-1 setup has been validated for only the test specimen geometries shown in the standard, up to the dimensional limitations in the standard. Alternative configurations should not be used, including boxes mounted on pipes, except for the planar specimen with a protruding box described above.

Classification by insulation rating with ISO 22899-3 may be performed using the one of the following three test specimens:

a) A tubular specimen with a mounted CPCE item, in the test configuration where the specimen is in the centre of the fire compartment, or;

b) A planar specimen with a protruding box of side length 260 mm +/- 10 mm, constructed from the same plate thickness as the surrounding panel or from a frame representative of the intended use attached to the panel (as shown in Figure 3)

c) An actual item of CPCE, in the test configuration where the specimen is in the centre of the fire compartment.

All joints, penetrations such as ducts, control cables, drain plugs, ventilation grilles, etc., and integrated features critical to the fire-resistance of the CPCE, such as doors, control panels, etc., shall be tested in a manner representative of the actual feature for which classification is sought.

NOTE: Testing of penetrations within the exact design of PFP system for every end application is not practical. It is reasonable practice to assume the design of a tested penetration is applicable within the complete scope of the surrounding PFP system, subject to agreement on test requirements with the AHJ or product evaluator. These requirements typically include test of a maximum size and demonstration of a maximum fire resistance period.

Corner joints, butt joints and overlap joints shall be considered as separate joint types and tested individually. The type and orientation of joints or fittings used to secure the protection system shall be the same as used in actual site installation, so far as is practicable.

Air gaps present shall be measured and recorded on the test report and shall form part of the overall system and classification.

Jet fire testing of joints, penetrations and integrated features may, in principle and at the discretion of the authority having jurisdiction, be used to demonstrate performance of these components in hydrocarbon pool-fire testing. However, hydrocarbon pool-fire testing may not be used to demonstrate performance of these components in jet fire.

Figure 3 — ISO 22899-1 test specimen for CPCE systems including raised features and edge/corner details

The erosion thickness concept may be applied to CPCE and use to calculate the thickness of insulation required over that required for pool fire testing. This approach may not be used to reduce jet fire PFP system requirements below the scope of the jet fire test data, nor may it be used to modify design details of penetrations, integrated features, or joints, from the designs tested to jet fire.

The internal heat transfer processes result in the thermal response of a vessel wall deviating significantly from the ‘standardised’ conditions under ISO 22899-1 or -3 testing. The magnitude of variation will depend on whether the wall is in contact with liquid or vapour, and whether it is subject to relieving/blow-down conditions. In the absence of a dedicated test standard or adequate published research on the subject, it is commonly assumed that the response of the PFP will be independent of the heat loss conditions on the non-fire-exposed surface of the substrate, and to base the PFP thickness on a suitable representative vessel pool fire test (such as ISO 21843) in conjunction with a jet fire erosion thickness calculated based on structural steel or tubular test specimens.

Bibliography

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