Bushfire Coatings Guide for Wood Poles · Bushfire Coatings Guide for Wood Poles V0 COMMERCIAL IN...

Bushfire Coatings Guide for Wood Poles V0 COMMERCIAL IN CONFIDENCE of 11

Bushfire Coatings Guide for

Wood Poles

Contents 1 SUMMARY .................................................................................................................................................. 2

2 BACKGROUND ............................................................................................................................................ 3

3 CHARCOAT CC - IN BRIEF ............................................................................................................................. 4

4 HOW TO ASSESS THE OPTIONS ................................................................................................................... 5

5 CHARCOAT CC FAQ ..................................................................................................................................... 7

14 January 2020

www.shieldcreteaustralia.com.au

[email protected]

1800 364 776

http://www.shieldcreteaustralia.com.au/

mailto:[email protected]


1 SUMMARY Recent bushfire activity in Australia has renewed interest in the in-situ application of fire-resistant coatings for wood poles and bridge piles/beams in high fire risk areas. Whilst equally applicable to wooden bridges, this document summarises the learnings from more than 12 years of testing different products on power poles by Nathan Spencer (our Director) and others in the industry, and provides detail on the assessment process that was used to determine that Charcoat CC was a perfect fit for this application.

Bushfire coatings on poles have been used for more than 10 years now by Western Power. A number of utilities have trialled different systems in this time, but the trials have never turned into projects. In our experience, this has been due to one or more of the following;

• Lack of statistical issue – on a 10-year rolling average, utilities may only lose 10-50 poles per year in bushfires. Compared to an asset base of 500,000 or more. Hence it is not seen as statistically relevant, even though 300+ may be lost in a single event. As time goes on though, the more fire resistant creosote treated and untreated poles are being replaced with CCA poles, which will increase losses per event.

• Unable to financially justify – when looking at the issue of the number of poles in high risk areas and the cost involved in coating them as a whole, the cost-benefit doesn’t add up when there is no ability to rank each pole by a more refined risk ranking system and target the highest risk poles each year.

• Timing – Large organisations can be reactionary in nature. With the financial strains that are placed on utilities by regulators if bushfires aren’t front-of-mind, then bushfire protection may be rejected when trying to gain budget approvals.

Now though, we can model the risk of bushfire attack for any given season based on previous fires, historical rainfall and other climate data1, as well as age of line, pole treatment, and proximity to various levels of vegetation. We can program in a work package to enable the highest risk poles to be coated prior to the next bushfire season, and we can even track fires in real time relative to the network and pre-emptively coat poles that may be in the fire path (if appropriate planning and safety measures are in place).

Coating costs can be a fraction of the cost of line and pole replacement, and can help get power back on to affected communities faster (if not preventing loss altogether).

This document gives further information about how to assess different technologies. For details of the turn-key service that we can provide with our industry partners, contact us on 1800 364 776 or [email protected]

1 Pheonix Rapidfire developed by the Bushfire CRC can be a useful tool in the process.

mailto:[email protected]


2 BACKGROUND Shield Crete Services Australia director Nathan Spencer (working for Koppers Wood Products at the time) in 2007/08 initiated the use of fire retardant (FR) Polyurea/urethane hybrid coatings for Western Power to help protect its assets against bushfire threat. Ultimately, it has been applied to more than 120,000 new hardwood and softwood poles before they are installed in the network. A previous latex product from the US, which is still used for touch-up was not a very effective long or short-term solution. The FR Polyurea hybrid used in WA has performed reasonably well, but has some significant drawbacks;

• It is only practical for factory application – it has been reported to us that only around 40% of coated poles go into areas of significant fire risk therefore 60% are needlessly coated.

• It does not adhere very well to timber (mainly due to the moisture in the timber)

• It is hard to ensure the required thickness is achieved (from a QA/QC perspective)

• It is damaged by the shrink-swell of the timber (see image to the right).

• It can trap moisture in the timber, which in some (not all) cases can lead to accelerated decay.

• Being polyurea based, touch-up products don’t adhere well, and the repair product only lasts 4-10 years before it requires re-coating.

• Re-coating after a fire is not easy.

• Despite being a rugged coating, it is still vulnerable to handling and transport damage. Since the development of the FR polyurea/urethane hybrid, we have tested many different products including;

• Fire retardant wraps

• FR coated stainless mesh

• Porcelain paint

• Ablative cable coatings

• Intumescent cable coatings

• Intumescent coatings for steel

• Hand-applied FR urethanes

• Other FR polyureas

• Intumescent Epoxies

• Fibreglass reinforcing wraps

• Thin-film bushfire coatings for BAL ratings. From the research and testing, we learnt a lot about protecting poles from bushfire attack, including;

• Factory coating can lead to 60% of poles being needlessly coated as it is hard to know where the poles will be placed at the time of order.

• Wraps and mesh are reasonably fast to apply, but create issues with inspectability of the poles, fuel growing between the mesh and the pole, plus application issues with reinforced poles or poles with lots of attachments.

• Porcelain paint is too brittle in practice and is too thin at economical application rates to resist a decent fire.

• Ablative cable coatings do not have enough resistance to economically resist a decent fire, most dry too slowly, and do not breath very well.


• Hand applied urethanes perform well but involve considerable waste and are messy to apply.

• Intumescent epoxies are too brittle and don’t adhere to the timber unless it is kiln dried. They trap moisture in the pole, and bubble off when burnt with moisture in behind them.

• Intumescent coatings for steel require too many coats, do not dry fast enough, and cannot stand up to the environment as well as other solutions.

• Fibreglass wraps are mainly used for reinforcement of poles in the US, but is not a viable solution due to cost, inspectability and moisture trapping issues.

• Thin-film fire resistant coatings used in Australia to give timber BAL ratings of up to BAL40 for housing do not give the required fire protection for poles, and they do not bridge cracks or move with the wood substrate

• Spray application of product is preferred for field application due to speed, consistency and control of thickness.

Charcoat CC is the only fire preventative coating that meets all our stringent criteria.

3 CHARCOAT CC - IN BRIEF Charcoat CC is the most advanced cable coating on the market. Unlike its competitors, it is intumescent (it expands to insulate the substrate as shown in the image to the right) but is external grade and is designed to adhere to difficult substrates. It maintains integrity of cables for 90min under 1100°C fire conditions and stands up to bushfires exceptionally well for such a thin coating of 1.5mm thick minimum recommended for bushfire (1.6mm minimum for cable coating to satisfy FM3971).

It is water based (single pack), zero halogen, no itchy glass fibres and non-hazardous. Charcoat CC has exceptionally low smoke generation and toxicity, and it performs similar to concrete in that regard.

Charcoat CC is easy to apply by airless spray but can be applied by brush in small areas for touch-ups as well.

It’s ability to resist damage and delamination as well as being able to move with the wood during wetting/drying cycles is the best we have seen.

Being a breathable coating means that the effects on the moisture content within the wood and resulting risk of decay and termites is no different to un-coated wood, if not a little better.

Charcoat CC is sourced from the US and stocked in Brisbane.


4 HOW TO ASSESS THE OPTIONS Following the research and testing accomplished over the last 13+ years, the table below demonstrates our standard criteria for assessing wood pole bushfire protection options and the outcomes for Charcoat CC.

Performance Criteria Description Charcoat CC

Ease of application in the field

Brush and spray application should be simple and equipment cost effective and capable of

being taken into rugged terrain. Factory applied systems are no longer considered.

Spray – Easy. Brush - Easy for touch-ups, not economical for full application.

Number of coats required (if a coating)

More than one is undesirable 1

Drying times (skin / fully cure)

As long as it skins off and is resistant to rain within 1-2 hours, it is considered satisfactory given the remote locations it is to be applied

in. Full cure in less than 7 days maximum.

30-60min skin, 3-6 days full cure, rain resistant after skinning.

Adhesion to damp timber

Needs to be able to stick to damp wood as this is typical for poles in the field, especially near ground line. Over time peeling occurs if adhesion is inadequate. Generally, this will exclude all but water insensitive coatings.

Excellent adhesion due to its water based adhesive

technology.

Application 50-100mm below ground?

Does backfilling while wet cause any issues? No issues, can backfill wet.

Effectiveness over cable guards, reinforcement, signs, ID tags?

The solution should be able to cater for the attachments, signage and identification on

poles without hindering the ability to view, or the serviceability of attachments.

Easy to mask signs/tags. Coating is applied over cable guards and

reinforcement, and down the top of the reinforcement/guard.

Ability to hammer sound without significant damage

Hammer sounding is key for any pole inspector to assist in determining the

condition of the pole. Having to remove the protection to do this, or having to repair it all

the time is undesirable.

Hammer sounding is done through the Charcoat CC coating

without significant damage.

Ability to visually inspect the pole

Post coating, an inspector still needs to be able to detect any surface irregularities on

poles and detect termites.

Charcoat CC follows the contours of the pole and does not hinder

normal visual inspection.

Ability to use Dig & Drill inspection technique

The method should not hinder, or be damaged by the digging and drilling for

regular pole inspection (if this method of inspection is still used)

Drilling and probing through Charcoat CC is possible. Re-

sealing is done by plugging with FR sealant, FR plastic plugs, or

touch-up with Charcoat CC. Resistance drill holes do not

require touch-up.

Ability to use NDT techniques

NDT techniques can have huge benefits to a utility; if the fire protection hinders the use of

the technique it is undesirable.

Tested with density meters, acoustic tomography, seismic and

vibration devices with no hinderance.

Ease of repair/touch-up option

Is it easy for an inspector or linesman to repair the coating if it is damaged during

service?

As simple as a tube of sealant or small tub of Charcoat CC and a

paint brush.


Performance Criteria Description Charcoat CC

Does the top-up material perform as well as the primary coating?

For some products, the top-up material does not perform as well as the original protection, hence the risk of damage or loss during fire is

higher.

No difference.

Ability of the coating to move with the timber

It doesn’t matter at what point the protection is applied, the pole will expand and shrink

through the seasons and through its life. This movement is strong enough to break steel bands, so the best products need to avoid

cracking and peeling due to movement.

Charcoat CC is permanently flexible and can sustain typical

movement (expansion and contraction). Even if it cracks the coating, the intumescence makes

damage in the crack unlikely.

Ability of the coating to breathe and maintain appropriate moisture levels.

Some protection options (including wraps and termite mesh) are known to increase

moisture in the timber, which increases chance of termite attack and decay. Ideally, coating should have no significant impact on moisture content, or a reduction in moisture

content lower than an un-coated pole.

Breathable – no significant moisture content increase, even

with open checks and no cap on a short sample.

Rejuvenation of fire damaged or old product that is no longer effective

Does the coating adhere to aged coating, or does the original coating have to be removed,

or is a tie coat required? How is the coating repaired after a fire comes through?

Charcoat CC sticks to aged Charcoat (and other coatings),

and can be scraped back and re-coated after a fire event.

Price

What is the long-term cost of the solution over the life of the pole? This should be total NPV cost divided by the number of poles that

will be protected in high-extreme fire risk areas to get a true risk reduction cost. Re-

coating, rejuvenation, touch-up, inspection and other costs directly caused by the

solution should be included.

Charcoat CC, on account of the above features is a very cost-

effective solution. Pricing usually based on ground

line diameter ranges of ≤300mm, 301-350mm, 351-400mm, 401-

450mm, ≥451mm.


5 CHARCOAT CC FAQ

5.1 WHAT THICKNESS IS RECOMMENDED?

We recommend a minimum of 1.5mm thick DFT, so we aim to allow 4kg/m2 of product, but this can vary slightly depending on application method.

5.2 HOW IS THE PRODUCT PACKAGED?

Charcoat CC comes in 22.5kg pails.

5.3 WHAT COLOURS DOES IT COME IN?

Standard is off-white. We can custom colour to suit upon minimum order.

5.4 WHERE IS IT MANUFACTURED?

United States of America

5.5 IS IT STOCKED LOCALLY?

Yes, we stock it in Brisbane and ship anywhere in Australia / New Zealand.

5.6 WHAT TRAINING IS PROVIDED?

To ensure that the product is properly applied, we conduct applicator training, which includes requirements for QA checks. For the warranty to be valid, the product must have been applied by a certified applicator with appropriate QA results made available to us.

5.7 WHY IS THE APPLIED PRICE BASED ON DIAMETER RANGES?

Because the larger the diameter, the more product is used per pole, and the longer the application takes.

5.8 WHAT IS THE RECOMMENDED MINIMUM NUMBER OF POLES PER

BATCH FOR ECONOMICAL PRICING?

100 poles is approximately one week’s work for one crew of two people and is the minimum recommended. However, the best cost-benefit will come with packages of 1000+ poles because the preparation, mobilisation, equipment and management costs can be amortised over more poles.

5.9 WHAT HEIGHT IS RECOMMENDED FOR COATING?

Based on studies done by Ausnet Services more than 10 years ago, and through Western Power experience, we recommend coating down to 50-100mm below ground and up to 1.8m above ground line as a minimum (2m AGL recommended).

5.10 CAN IT HANDLE SUBSTRATE MOVEMENT?

There are two aspects to this answer; maintenance of integrity and adhesion with movement, and whether cracks in the coating that may form with extreme movement (that can crack steel) affect the protection offered by the coating. In short, the intumescent property of the coating bridges significant gaps in the coating and the coating maintains integrity and adhesion during movement of the wood.

As an example, the CCA treated pine post in Figure 1 was coated after checking had already started (Figure 2). The checks are filled with ease, but you can also tape them to avoid wasting product.


Figure 1: Largest check in the pole before coating

Figure 2: Largest check in the pole after coating

The above post was buried approximately 300mm into the ground and left standing in full exposure from 18 February 2017 to 21 May 2017. The environmental conditions the pole experienced during this time were as follows;

• Maximum temperature 37.8°C, minimum temperature 4.9°C,

• Total rainfall of 374mm (~130mm per month average),

• The soil was a gravelly clay,

• There was no pole cap.

Moisture contents were taken at 25mm below the surface with the results summarised in Table 1. Note that the coating finished approximately 1600mm above ground.

Table 1: Moisture content readings

Approx. height above ground (mm) East Side West Side

100 15.4% 17.1%

1550 18.9% 16.4%

1700 15.9%

2050 12.2%


The values in Table 1 are surprisingly low considering there was no pole cap and 374mm of rain fell within 3 months and there were open checks extending through the cut-off point of the coating (Figure 4). The coating over the check did appear to have stretched, but the coating was still intact (Figure 3). Note that the holes from the moisture meter were not filled before the pole was put through a burn trial and they did not affect performance (Figure 4).

Figure 3: Largest check in the pole before burning

Figure 4: Check open above the coating could allow moisture in behind the coating but no significant moisture

content increase was noted

5.11 WHAT DOES CHARCOAT CC LOOK LIKE AFTER IT BURNS?

The following images (Figure 5 and Figure 6) show the pole after a ENA bushfire test equivalent burn. As you can see, the intumescent coating puffed up and insulated the substrate.


Figure 5: Pole burning

Figure 6: After burn – first test. Arrow points to area that looked thinnest.

There was no blistering of the coating during the test, and the holes from the moisture meter could not be found in the charred areas as the coating intumesced and covered them over before the flame could ignite the underlying timber.

5.12 ARE THERE ANY TOXIC GASSES OR RESIDUES RELEASED DURING

BURNING?

Given the Charcoat CC is designed for use in buildings, tunnels, mines, subways, submarines, ships, oil rigs, etc., it cannot have any significant levels of toxic gasses produced when burning, and it doesn’t. In fact, the amount and type of gas produced puts it in the same class as concrete and other materials that are considered non-combustible. We can provide test reports on request.

5.13 HOW DO YOU RE-APPLY AFTER BURNING?

The charring is cleaned off (Figure 7 and Figure 8) to expose sound coating and then re-coated with Charcoat CC with minimal prep (Figure 9). The coating in Figure 9 was done with a brush rather than an airless sprayer or hand/trowel, so only 1mm WFT was achieved in addition to the remaining coating from the burn, and it took approximately seven minutes to complete.

5.14 CAN THE CHARCOAT CC BE USED TO CONTAIN CHAR FROM BURNT

CCA POLES?

Whilst we have not used it specifically for this, Charcoat CC should provide adequate containment of burnt CCA poles, as well as protection from future burns.


Figure 7: Charring removed, ready for re-coating.

Removal took less than 5min.

Figure 8: Close-up of thinnest looking area after charring

removed.

Figure 9: Re-coated pole ready for a second burn.

Figure 10: Pole during the second burn test.

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