FIRE ASSESSMENT REPORT FAR 4433multimedia.3m.com/mws/media/1090549O/615-external-fire...FIRE...

PROJECT NUMBER: ISSUE DATE: PAGE:

FC4433 3 June 2015 1 of 12

THE LEGAL VALIDITY OF THIS REPORT CAN ONLY BE CLAIMED ON PRESENTATION OF THE COMPLETE SIGNED PAPER REPORT. EXTRACTS OR ABRIDGMENTS OF THIS REPORT SHALL NOT BE PUBLISHED WITHOUT PERMISSION FROM BRANZ LTD.

1222 Moonshine Road Judgeford RD1 Porirua 5381 New Zealand T +64 4 237 1170 F +64 4 237 1171 [email protected] www.branz.co.nz

FIRE ASSESSMENT REPORT

FAR 4433

FIRE RESISTANCE OF STEEL DUCTS PROTECTED WITH 3M FIRE BARRIER

DUCT WRAP 615+ FOR EXTERNAL FIRE EXPOSURE

CLIENT

3M Australia Pty Ltd Building A, 1 Rivett Road North Ryde NSW 2113 Australia

REPORT NUMBER: ISSUE DATE: PAGE:

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ASSESSMENT OBJECTIVE

To assess the fire resistance level (FRL) for external exposure of horizontal or vertical

steel ducts protected with one layer of nominal 38 mm thick 3M Fire Barrier Duct Wrap

615+, in accordance with AS 1530.4 2005.

CONCLUSION

It is considered that horizontal or vertical steel ducts protected with one layer of

nominal 38 mm thick 3M Fire Barrier Duct Wrap 615+, as described in Section 3.1 of

this report, would achieve at least 180/180/180 FRL or 240/240/240 FRL respectively

if tested in accordance with AS 1530.4-2005.

The ducts may be constructed similarly to those tested in the referenced tests, or in

accordance with AS 4254.2-2012, subject to a minimum steel thickness of 0.8 mm

and a minimum joint rating of J3.

Horizontal ducts may be up to 1,250 mm wide x 1,000 mm high, passing through steel

framed, plasterboard lined or concrete or masonry walls, as described in this report,

having at least -/180/180 FRL.

Vertical ducts may be up to 1,250 mm x 1,000 mm, passing through concrete floors,

as described in this report, having at least 240/240/240 FRL.

Where the FRL of the wall or floor through which the duct passes is less than the

nominal FRL of the duct, the FRL of the duct is limited as described in Section 3.3 of

this report.

LIMITATION

This report is subject to the accuracy and completeness of the information supplied.

BRANZ reserves the right to amend or withdraw this assessment if information

becomes available which indicates the stated fire performance may not be achieved.

This assessment report may only be quoted or reproduced in full.

TERMS AND CONDITIONS

This report is issued in accordance with the Terms and Conditions as detailed and

agreed in the BRANZ Services Agreement for this work.


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CONTENTS

SIGNATORIES .................................................................................... 4

DOCUMENT REVISION STATUS ......................................................... 4

1. INTRODUCTION ..................................................................... 5

2. BACKGROUND ........................................................................ 5

3. DISCUSSION .......................................................................... 7

3.1 Proposed Construction .............................................................. 7

3.2 Test Standard .......................................................................... 8

3.2.1 Furnace Temperature ...........................................................................8

3.2.2 Furnace Pressure .................................................................................8

3.2.3 Duct Configuration ...............................................................................9

3.2.4 Duct Size .............................................................................................9

3.2.5 Failure Criteria .....................................................................................9

3.2.5.1 Structural Adequacy .............................................................................9

3.2.5.2 Integrity ............................................................................................ 10

3.2.5.3 Insulation .......................................................................................... 10

3.3 Penetrated Element FRL .......................................................... 10

4. CONCLUSION........................................................................ 11

FIGURES

Figure 1: Drawing of Penetration Details ................................................................12


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SIGNATORIES

Author

E. Soja Senior Fire Safety Engineer

Reviewer

P. C. R. Collier Senior Fire Testing Engineer

DOCUMENT REVISION STATUS

ISSUE NO. DATE ISSUED DESCRIPTION

1 3 June 2015 Initial Issue


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1. INTRODUCTION

This report gives BRANZ’s assessment of the fire resistance of steel ducts, passing

through concrete or masonry or steel framed, plasterboard lined walls, or concrete

floors, protected with one layer of nominal 38 mm thick 3M Fire Barrier Duct Wrap

615+. The ducts are assessed with respect to fire on the outside of the duct.

2. BACKGROUND

In Exova Warringtonfire fire resistance test No 324343 a nominal 1,000 mm wide x

500 mm high horizontal duct constructed from 0.8 mm thick steel, protected with one

layer of 3M Fire Barrier Duct Wrap 615+ (Duct Wrap), was tested in accordance with

BS EN 1366-1:1999 for external fire exposure.

The duct was installed extending nominally 4 m into the furnace and 2 m outside the

furnace, passing through a steel framed, plasterboard lined wall. Each duct section

had a vertical steel tie rod at mid length and mid width of the section. The duct had

steel support channels suspended from the roof of the enclosure with steel threaded

rods.

A short branch duct with a 90° elbow, of 250 x 250 mm cross section was attached to

the exposed section of the main duct.

The wall was constructed from nominally 50 mm wide steel framing, lined on each

face with two layers of 12.5 mm thick “Type F” gypsum plasterboard, and with the

cavity filled with nominal 50 mm thick mineral fibre insulation of nominal density

100 kg/m3.

The gap around the duct at the wall penetration was nominally 50 mm at top and

bottom and at each side. The gap was packed with Duct Wrap material with the

encapsulating material removed, with nominally 30% compression.

A collar constructed from nominal 200 mm wide strips of nominal 35 mm thick

Promatect L 500 board was formed at each side of the penetration. One strip was

placed against the face of the wall with the edge butting against the outside of the

duct, and another was placed against the outside face of the duct, butting against the

first strip. The strips were glued and screwed together at their intersections.

A strip of 100 mm wide by 2.7 mm thick 3M Fire Barrier Moldable Putty+ Pad was

installed between the duct and the collar, with the edge of the pad flush with the face

of the wall.

The Duct Wrap was applied transversely around the duct in strips nominally 610 mm

wide. The section adjacent to the wall on each side had a double layer of Duct Wrap,

with the inner layer butting against the collar leg that was against the duct surface,

and the outer layer butting against the other collar leg. Duct Wrap edges overlapped

nominally 100 mm at all joints.


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The Duct Wrap was held in place by steel bands around the duct and by welded steel

pins and friction fit washers at the bottom surface of the duct.

The duct achieved 187 minutes with no failure of integrity by sustained flaming, gap

gauge or cotton pad test. A failure of integrity by the volume flow rate criterion of the

test standard was recorded at 185 minutes, with consequent failure of insulation.

Failure by the smoke leakage criterion of the test standard was recorded at

168 minutes.

In Exova Warringtonfire fire resistance test No 319989 a nominal 1,000 mm x 500 mm

vertical duct constructed from 0.8 mm thick steel, protected with one layer of 3M Fire

Barrier Duct Wrap 615+ (Duct Wrap), was tested in accordance with

BS EN 1366-1:1999 for external fire exposure.

The duct was installed extending nominally 2 m into the furnace and 2 m outside the

furnace, passing through a 150 mm thick aerated concrete floor. Each duct section

had a horizontal steel tie rod at mid height and mid width of the section. The duct had

steel support angles fixed to the longer faces of the duct and extending onto the top

of the floor at either side of the duct.

The gap around the duct at the floor penetration was nominally 50 mm on all sides.

The gap was packed with Duct Wrap material with the encapsulating material

removed, with nominally 30% compression.

A collar constructed from nominal 200 mm wide strips of nominal 35 mm thick

Promatect L 500 board was formed at each side of the penetration. One strip was

placed against the face of the floor with the edge butting against the outside of the

duct, and another was placed against the outside face of the duct, butting against the

first strip. The strips were glued and screwed together at their intersections and

screwed to the floor.

A strip of 50 mm wide by 2.7 mm thick 3M Fire Barrier Moldable Putty+ Pad was

installed between the duct and the collar. The edge of the pad was flush with the face

of the floor on the underside, and against the top edge of the support angle above the

floor.

The Duct Wrap was applied transversely around the duct in strips nominally 610 mm

wide. The sections directly above and below the floor had a double layer of Duct Wrap,

with the inner layer butting against the collar leg that was against the duct surface,

and the outer layer butting against the other collar leg. Duct Wrap edges overlapped

nominally 100 mm at all joints.

The Duct Wrap was held in place by steel bands around the duct and by welded steel

pins and friction fit washers at the long faces of the duct.

The duct achieved 245 minutes with no failure of integrity or insulation.


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3. DISCUSSION

3.1 Proposed Construction

It is proposed that horizontal or vertical steel ducts may be constructed similarly to

those tested in the above referenced tests, or in accordance with AS 4254.2-2012,

subject to a minimum steel thickness of 0.8 mm and a minimum joint rating of J3.

The duct is to be wrapped with one layer of nominal 38 mm Duct Wrap installed

similarly to the tested wrap, for a fire resistance level (FRL) of up to 180/180/180 for

horizontal ducts and 240/240/240 for vertical ducts. Horizontal ducts may be up to

1,250 mm wide x up to 1,000 mm high. Vertical ducts may be up to 1,250 mm x

1,000 mm.

For horizontal ducts the wall may be of concrete or masonry, or steel framed and lined

with plasterboard. The wall is to have been previously tested or assessed to have a

FRL as is required for the duct. The wall need not be loadbearing as the duct is self-

supporting.

For plasterboard lined walls the opening is to be framed on all sides with steel framing

similar to the wall studs and the inside face of the opening is to be lined with the same

lining as the faces of the wall. Mineral fibre insulation is to be placed to fill the wall

cavity, extending at least 200 mm from the opening in the horizontal and vertical

directions

For vertical ducts the floor is to be of concrete, at least 150 mm thick, and is to have

been previously tested or assessed to have a FRL as required for the duct.

The clearance between the duct and the inside face of the opening is to be a maximum

of 50 mm. The clearance gap is to be filled with Duct Wrap with the encapsulating

material removed.

A collar is to be formed from 35 mm Promatect L 500 board constructed and installed

similarly to the tested duct collar, including the 2.7 mm 3M Fire Barrier Moldable

Putty+ Pad between the Promatect L 500 and the duct (100 mm wide for horizontal

ducts, at least 50 mm wide for vertical ducts).

The Duct Wrap is to be applied to the duct in transverse bands, with the ends of each

band overlapping by at least 100 mm, closed with 3M aluminium foil tape. For

horizontal ducts the end joint of each band is to be formed on the top of the duct. The

first band around the duct on each side of the wall or floor is to be butted against the

Promatect L 500 collar section that is adjacent to the duct. The section of duct

adjacent to the wall or floor is to have a second layer of Duct Wrap over the first layer

and butting against the collar section that is perpendicular to the duct.

100 mm overlap joints are to be formed between adjacent bands of Duct Wrap.


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The Duct Wrap is to be secured to the duct by means of bands of stainless steel

12.7 mm wide x 0.4 mm thick, tightly clamped around the Duct Wrap at mid width of

each joint, and nominally mid width of each Duct Wrap band.

In addition the Duct Wrap is to be fixed to the bottom surface of horizontal duct, and

the long sides of vertical ducts, using welded 2.7 mm diameter steel pins and friction

fit clips at nominally 350 mm centres across the duct, starting within 170 mm of each

edge of the duct. The pins are to be nominally mid-way between the steel bands.

The proposed details are outlined on Figure 1 attached to this report.

3.2 Test Standard

The tests were conducted in accordance with BS EN 1366-1:1999. The proposed

construction is to be assessed in relation to AS 1530.4-2005. The following outlines

the significant differences between these two standards in relation to the expected

performance of the duct.

3.2.1 Furnace Temperature

The heating conditions within the furnace as tested were as required by EN 1363-1

1999. The specified temperature curve with time is identical to that specified in

AS 1530.4-2005.

The furnace temperature is measured differently for the two test standards, with

EN 1363-1 requiring the use of plate thermometers where AS 1530.4-2005 requires

mineral insulated metal sheathed thermocouples.

Twilt and van de Leur1 examined thermal exposure in fire resistance furnaces with the

temperature controlled by various types of measuring device, and concluded that, for

an insulating specimen, the temperature is likely to be higher when the furnace is

controlled with plate thermometers than when controlled with small diameter

thermocouples.

Therefore it is expected that the test temperature was more severe for the test than

is required for AS 1530.4-2005.

3.2.2 Furnace Pressure

The pressure within the furnace relative to atmospheric pressure is required to be

15 ± 3 Pa at the mid height of the duct for EN 1363-1 1999. For AS 1530.4-2005 a

neutral pressure plane is to be established 500 mm above the notional floor level. For

the duct as tested the pressure was higher than would be required for AS 1530.4-

2005, which is considered more onerous.

1 Van de Leur, P.H.E, Twilt, L, “Thermal Exposure in Fire Resistance Furnaces”, Fire Safety Science – Proceedings of the Sixth International Symposium, IAFSS, 1999.


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3.2.3 Duct Configuration

For external exposure to EN 1363-1 1999 the duct is as described in section 2 of this

report. An internal pressure of -300 ±15 Pa relative to atmospheric pressure is to be

established within the duct and maintained throughout the test.

For external exposure to AS 1530.4-2005 the duct is required to pass through the

furnace with at least 2000 mm exposed to the furnace conditions, and extend beyond

the furnace by at least 500 mm at each end. The duct is to be open at each end and

an air flow of 1 ± 0.2 m/s is to be established through the duct.

The negative pressure within the duct as tested would be expected to draw hot gases

into the duct through any holes that may form in the duct. The relative pressure

between outside and inside of the duct is significantly less when tested to AS 1530.4-

2005, which is considered similar to or less onerous than the conditions as tested.

Ducts constructed in accordance with AS 4254.2-2012, subject to the limitations noted

in section 3.1 of this report, would have similar strength and stiffness to the tested

ducts, and would be expected to perform similarly.

3.2.4 Duct Size

For ducts tested at the standard size of 1,000 x 500 mm BS EN 1366-1 1999 allows

the dimensions to be increased to a maximum of 1,250 x 1,000 mm. AS 1530.4-2005

allows application of the test result to ducts of the same size or smaller than the duct

tested.

For the purpose of this assessment the maximum size permitted under BS EN 1366-1

1999 may reasonably be considered as being the tested size, and therefore the result

would also be applicable up to the same maximum duct size under AS 1530.4-2005.

3.2.5 Failure Criteria

3.2.5.1 Structural Adequacy

In AS 1530.4:2005 structural adequacy failure of the duct is deemed to have occurred

when the duct collapses in such a manner that the duct no longer fulfils its intended

function.

In BS EN 1366-1:1999 there is no corresponding failure criterion.

As tested, the duct retained its original shape without significant collapse in the vicinity

of the penetration through the wall or floor, and this is taken as indicating that the duct

continued to fulfil its intended function. Therefore a structural adequacy to

AS 1530.4:2005 of at least 187 minutes would be expected for the horizontal duct,

245 minutes for the vertical duct.


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3.2.5.2 Integrity

In AS 1530.4:2005 the integrity performance of the duct is determined in relation to

the penetration through the surrounding element and the section of duct outside the

furnace. Failure is deemed to have occurred on ignition or glowing of a cotton pad

after an application of 30 seconds, or on observation of flaming on the unexposed

surface for 10 seconds.

In BS EN 1366-1:1999 failure of integrity is determined on the unexposed section of

the duct and the penetration through the surrounding element. Failure is deemed to

have occurred on ignition or glowing of a cotton pad after an application of

30 seconds, on the occurrence of gaps of specified size or on observation of flaming

on the unexposed surface for 10 seconds. Failure is also determined based on volume

flow rate through the duct surface within the furnace.

The failure criteria of AS 1530.4:2005 are therefore a subset of the failure criteria of

BS EN 1366-1:1999.

As tested the horizontal duct did not fail either the flaming or the cotton pad test for

the 187 minute duration of the test, therefore the integrity result to AS 1530.4:2005

would be expected to be at least 187 minutes.

The vertical duct did not fail any of the relevant criteria therefore the integrity result to

AS 1530.4:2005 would be expected to be at least 245 minutes

3.2.5.3 Insulation

For both test standards the insulation performance is determined based on

thermocouples placed on the duct and surrounding construction at specified locations.

The locations specified by the two standards are equivalent.

For BS EN 1366-1:1999 the insulation performance is determined based on the

average temperature rise of some of the specified thermocouples, or maximum

temperature rise of any of the specified thermocouples. Failure also occurs on any

failure of integrity. For AS 1530.4:2005 only the maximum temperature rise is

considered.

As tested, none of the specified thermocouples exceeded the maximum temperature

rise criterion and therefore the insulation performance in accordance with

AS 1530.4:2005 would be expected to be at least 187 minutes for the horizontal duct,

245 minutes for the vertical duct.

3.3 Penetrated Element FRL

Where wall having a FRL less than the nominal FRL of the duct, the Structural

Adequacy of the duct is limited to the greater of the Structural Adequacy and Integrity

ratings of the wall. The Integrity and Insulation of the duct are limited to the Integrity

and Insulation of the wall.


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Where a duct is installed through a floor having a FRL less than the nominal FRL of

the duct, the duct is limited to the same FRL as the floor.

4. CONCLUSION

It is considered that horizontal or vertical steel ducts protected with one layer of

nominal 38 mm thick 3M Fire Barrier Duct Wrap 615+, as described in Section 3.1 of

this report, would achieve at least 180/180/180 FRL or 240/240/240 FRL respectively

if tested in accordance with AS 1530.4-2005.

The ducts may be constructed similarly to those tested in the referenced tests, or in

accordance with AS 4254.2-2012, subject to a minimum steel thickness of 0.8 mm

and a minimum joint rating of J3.

Horizontal ducts may be up to 1,250 mm wide x 1,000 mm high, passing through steel

framed, plasterboard lined or concrete or masonry walls, as described in this report,

having at least -/180/180 FRL.

Vertical ducts may be up to 1,250 mm x 1,000 mm, passing through concrete floors,

as described in this report, having at least 240/240/240 FRL.

Where the FRL of the wall or floor through which the duct passes is less than the

nominal FRL of the duct, the FRL of the duct is limited as described in Section 3.3 of

this report.


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Figure 1: Drawing of Penetration Details

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