Testing Heat Resistant Ropes

Introduction

Flare Tip Replacement 600x800
Industrial rope access is a term used to describe a set of techniques for performing work at height. Generally speaking, rope access technicians perform their trade while suspended in a harness from a rope, with a second rope system in place as a backup safety arrangement in case the main line should become damaged. For more information about rope access, please visit www.sprat.org, or www.irata.org , both global trade associations for rope access.

Rope access technicians perform an astonishing variety of work, in just about every corner of the world, with an incredible record of safety. Their activities may range from inspecting pipelines on the North Slope of Alaska, to upgrading wind turbines in Tierra del Fuego, and maybe even washing the windows on your apartment building. A large amount of rope access work is done in the petroleum industry, performing inspections, making repairs, and upgrading infrastructure. The refinery environment presents an additional hazard to rope access techs, which is that much of the workings of a refinery require steam, which is piped at high temperatures ( approximately 700 F) all around the refinery.

 

The question was posed to us:

“What would happen if a rope supporting a tech were to come in contact with a steam pipe? How long would it last?”

To answer this question, we first did some background investigation, to determine the factors involved. The following information was noted:

Thermal Resistance Fibers Chart
  • Almost all ropes used for rope access work are made of either polyester or nylon, also sometimes referred to as polyamide. Both of these fibers have a melting point of approximately 400F. However, its interesting to note, that they begin to experience significant strength loss well before that, around the 200 F mark. ( Interestingly, as they get colder, nylon ropes actually gain a bit of strength, down to about -40F)
  • Average temperature of a steam tracing pipe is approximately 700F, and they are usually made of steel and are usually about 4 inches in diameter.

  • Fibers do exist which have a higher resistance to heat, the ones suitable to making rope are in the family of aramids, which are commonly known by the tradenames of Technora or Kevlar.

  • Rope access technicians come in a variety of sizes and weights, but for testing purposes 300 pounds is commonly used to represent a full sized worker and their equipment.

Simply by looking at the information above, we could be quite confident that a nylon or polyester rope that came in contact with a steam pipe would melt.

The question we then needed to answer was:

“How long will a weighted rope in contact with hot pipe take to melt through?”

Hot Pipe Test Setup 900x675
To answer this, we created an electrically heated pipe which was capable of reaching the 700 degree mark, and could be mounted in our hydraulic tensile tester, and pulled to 300 pounds. We decided to test the following types of rope:
  • Our standard polyester HTP, commonly used in rope access.
  • Our Tech11, which has an aramid sheath braided over a nylon core.
  • Our H3Tech11, which has an aramid sheath and core as well.
  • Our newest 11mm Tech HTP, which has an aramid sheath and polyester core.

These ropes were tested using the described arrangement, with the following results.

Sterling Rope Hot Pipe Results Summary

Test Temp (F): 700
Pipe Diameter (in): 4
Rope Contact (deg): 180

 

H3Tech11

Tech11

H3Tech125

Tech125

7/16HTP

TechHTP

Time (s)

600

600

600

600

34

600

Load Held (KN)

2.00

2.00

2.00

2.00

0.31

2.00

Residual ABS (KN)

37.83

13.14

39.11

13.56

0

8.64

Control ABS (KN)

44.94

44.50

47.80

40.40

35.20

38.94

Strength Retained

84.2%

29.5%

81.8%

33.6%

0.0%

22.2%

HTP

This 100% polyester rope performed poorly. Essentially it melted through as fast as the tester could pull, like the proverbial “hot knife through butter.” If this rope were to come in contact with a hot pipe with a technician suspended from it, the failure would be almost instantaneous.

Tech 11

Tech11 test results
This rope exhibited an interesting behavior in the test. As it was heated over the pipe, the two tracer yarns, which are actually polyester, melted. The rest of the sheath is Technora and did not melt or fail during the 10 minutes of the test. However, the nylon core inside became liquefied where it was around the hot pipe and that liquid nylon came squirting out of the tiny holes in the sheath left by the two tracers which had melted away. The effect was a bit like squeezing toothpaste out of a tube. After the ten minute test, we pulled the rope to failure, which revealed a residual strength on average over several tests of about 13 kN, compared to the original strength when new of about 44 kN. While this represents a significant loss of strength, the residual number is enough to provide some safety to a technician.

H3Tech11

This 100% Technora (both sheath and core) rope was the least interesting test to watch. It simply pulled on the hot pipe with little to no effect, other than a slight color change, making it look a bit “toasted.” When tested for residual strength, it showed a residual strength of almost 38 kN, compared to an original strength of 44.5 kN.

Tech HTP

The Tech HTP performed somewhat similarly to the Tech 11, in that the core appeared to have melted while the sheath remained relatively intact. Though it should be noted that the sheath of the TechHTP is 100% aramid, including the tracers, unlike the Tech11.  All of the specimens held the test load during the ten minute duration, with an average residual strength of about 8.6kN, compared to the original strength of 38kN. This is still more than enough to hold a technician’s weight until they can be safely rescued.

Conclusion

So, what conclusions can we draw from this testing? Well, we know that standard practice is to take all possible steps to avoid the rope coming in contact with a hot pipe. However, in the case where it accidentally may meet a pipe, these aramid fibers offer a significant advantage and level of protection to the worker. For more information, copies of test reports, or to discuss various options in rope, contact us any time.

 

Intro image and header image taken by Ben Erdman

 

Shop our Full line of Heat Resistant Tech Series Ropes

 

Tactical Response

Tactical Response

A favorite of the pararescue community and offers extreme strength in a lightweight and compact size. Technora sheath with a nylon core. 9.5 mm diameter.

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Tech HTP

Tech HTP

A low-elongation rope suited for the harshest conditions where heat and abrasion resistance are critical. Technora sheath with polyester core. 11 mm diameter.

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Tech11

Tech11

A G-rated 11 mm rope for extrem abrasion and heat resistance for punishing rescues and tough rope access jobs. Technora sheath/nylon core. 11 mm diameter.

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H3 Tech11

H3 Tech11

Massively heat resistant and built to perform flawlessly under some of the most dangerous conditions most workers will ever face. Technora sheath/technora core. 11 mm diameter.

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Tech125

Tech125

Extreme durability in general-use size rope designed for roof rescue and other high heat and abrasion intensive activities. Technora sheath and nylon core. 12.5 mm diameter.

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H3 Tech125

H3 Tech125

The burliest of our tech series. Heat and abrasion resistant to an unparalelled degree. The H3 Tech125 will stand up to the worst hazards you will encounter on a jobsite. Technora sheath with a technora core. 12.5 mm diameter.

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