hook knife tip shape / puncture resistant glove … s/2016spring/safety...occupational safety and...

Occupational Safety and Health ConferenceSpring, 2016

Philadelphia, PA

Hook Knife Tip Shape / Puncture Resistant Glove Testing

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Eversource Energy

Hook Knife Tip Shape / Puncture Resistant Glove Testing

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At approximately 9:15 AM on 09 September 2015, a UG #2 was assigned work

UG #2 was in the process of preparing to install an elbow on a single phase

conductor size 4/0. UG #2 was using a common hook knife to make a cut into

the jacket, when the knife he was using in his right hand slipped off the jacket of

the cable and struck his left hand.

The knife pierced the Kevlar gloves he was wearing between his left thumb and

index finger and penetrated into his left hand causing a puncture wound that

required a surgeon because of damage to an artery in the hand.

Background

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Limited distance between left hand and where cut being made

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Action: Risk reduction using common hook knife

Summary: A series of glove puncture tests were conducted to determine how to reduce the risk of hand injury when using a hook knife. The tests were performed on four types of work gloves with three different points on the blade. Thirty-eight tests were completed in all.

Action & Methods

Objective: To evaluate the benefit of modifying a pointed hook knife tip in order to reduce chance of puncturing. Conduct testing with 4 Kevlar work glove designs to verify what should be kept in Eversource stock.

Test Description:

1. Each test knife was fitted with a hinge pin (pivot point) approximately 6 in. from the tip. Mule tape attached 3 in. from the tip, other end was attached to a measuring scale.

2. Test gloves were filled w/ a potato simulating flesh and placed under the knife tip. Knife pivot was clamped in vise.3. By pulling downward on the scale via a 24 in. mule tape, a steady measured force was applied on the midpoint of the knife.4. Force was applied to a maximum amount (80 lbs-limit of scale), or until pulling resistance dropped rapidly and it felt that the glove was pierced.

Puncture Test Set-Up

Presenter

Presentation Notes

After initial analysis of the incident and coming to the reality that these tools are standard use in the field, we developed a hypothesis that slightly rounding off the point on the standard hook knife would significantly decrease the potential to puncture an employees Kevlar glove(s) but not hamper the everday functionality of the tool. The idea of this test was to mimic the force of a hook knife if it were to make inadvertent contact with an employee in a field atmosphere. This test would also give us verification that the Puncture Rating on the gloves currently distributed throughout Eversource was sufficient.

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Knife # Glove TypeTip

Diameter (Approx.)

Test # In-lbs.at puncture

Description / Summary

Results Palm of Glove Picture Back of Glove Picture

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(Mid Blunted)

Youngstown (Palm) 3/16" 1 80+ lbs. / 80+ lbs.

At 80+ lbs. of downward force, there was a puncture to the layers w/ Kevlar

material.

Youngstown (Back) 3/16" 2 80+lbs (puncture) /

80+lbs (no puncture)

First attempt, 80+lbs of force punctured the layers w/ Kevlar

material.

Second attempt, 80+lbs of force did not puncture the layers w/ Kevlar.

2

(Mid Blunted)

SHOWA S-Tex 350 (Palm)

3/16" 3 34 lbs. / 50 lbs.At 34-50 lbs. of downward force,

there was a puncture to the Hagane Coil fiber material w/ nitrile coating.

N/A - similar to test 11 below N/A - similar to test 12 belowSHOWA S-

Tex 350 (Back,

uncoated)

3/16" 4 17.8 lbs

At 17.8 lbs. of downward force, the knife penetrated the skin but did not rip the uncoated Hagane coil fiber

material. During testing, resistance could not be felt at the puncture point.

2

(Mid Blunted)

Salisbury (Palm) 3/16" 5 80+ lbs. / 80+ lbs.


material.

Salisbury (Back) 3/16" 6 80+ lbs. / 80+ lbs.


material.

2

(Mid Blunted)

Endura 4/3 (Palm) 3/16" 7 80+ lbs. / 80+ lbs.

At 80+ lbs. of downward force, there was a puncture to the leather w/

Kevlar liner.

Endura 4/3 (Back) 3/16" 8 80 lbs. (puncture) /

80+ lbs. (no puncture)

First attempt, 80+lbs of force punctured the leather w/ Kevlar liner.

Second attempt, 80+lbs of force did not puncture the leather w/ Kevlar

liner.

Presenter

Presentation Notes

Testing was conducted on both sides of each glove type (Palm and Backhand). 3 different diameters of knives were used during the testing methods: 3/16” – Slightly rounded tip 5/16” – More aggressive rounding 1/16” – Standard issue hook knife – Sharpest point The first series of tests were performed using a 3/16” diameter Hook Knife. All gloves, except for the Showa S-Tex 350, performed well during these methods. It took full capacity of the scale used (80 LBS.+) to receive any puncturing of the gloves. It is our conclusion that the gloves began to puncture more so because the potato was giving in and the blade of the knife was able to dig into the material rather than the point (3/16”) of the hook knife puncturing through. With these optimistic results, we did not test with the 5/16” rounded tip.

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Knife # Glove TypeTip

Diameter (Approx.)

Test # In-lbs.at puncture

Description / Summary

Results Palm of Glove Picture Back of Glove Picture

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(No Blunting) Standard

Pointed Hook Knife

Youngstown (Palm) 1/16" 9 14 lbs. / 18 lbs.

At 14-18 lbs. of downward force, there was a puncture to the layers w/

Kevlar material.

Youngstown (Back) 1/16" 10 23 lbs. / 24 lbs.


Kevlar material.

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Pointed Hook Knife

SHOWA S-Tex 350 (Palm)


there was a puncture to the HaganeCoil fibers w/ nitrile coating.

SHOWA S-Tex 350 (Back)


there was a puncture to the Haganecoil fiber material (uncoated).

3


Pointed Hook Knife

Salisbury (Palm) 1/16" 13 17 lbs. / 18 lbs.


Kevlar material.

Salisbury (Back) 1/16" 14 31 lbs. / 38 lbs.


Kevlar material.

3


Pointed Hook Knife

Endura 4/3 (Palm) 1/16" 15 22 lbs. / 22 lbs.

At 22 lbs. of downward force, there was a puncture to the leather w/

Kevlar liner material.

Endura 4/3 (Back) 1/16" 16 21 lbs. / 24 lbs.

At 21-24 lbs. of downward force, there was a puncture to the leather w/

Kevlar liner material.

Presenter

Presentation Notes

All gloves performed poorly when testing methods were conducted with the standard hook knife – 1/16” sharp point. The point of the standard hook knife was puncturing at very little exerted force.

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Findings & Conclusion

As a result of our findings, the company is transitioning all pointed hook knives to a 3/16” tip design for both Overhead and

Underground departments.

Fig.1 - 5/16” Fig.2 – 3/16” Fig.3 - Point

The pointed tip of knife 3, a standard hook knife, easily pierced ALL TYPES OF GLOVES and quickly sliced deeper after initial puncture.

The blunted tips of knife 2 pushed into the "potato flesh"; however, the force it took to puncture the Youngstown, Salisbury, and Endura gloves was 80+ lbs.

The Showa gloves do not provide puncture protection on the hand backside because the tip pushed in with a force of 17.8 lbs. The Nitrile coated palm provided more protection.

A moderately blunted knife tip similar to knife 2 with a diameter of approx. 3/16" is recommended for general use over the standard pointed knife.

Presenter

Presentation Notes

Given the results of our testing methods, our Hypothesis was proven that slightly rounding off the point on the standard hook knife will significantly increase the protection level of the Kevlar gloves within Eversource. As a result of our findings, the company is transitioning all pointed hook knives to a 3/16” tip design for both Overhead and Underground departments. The company will also be standardizing what gloves can be used during cutting operations, which will include the Youngstown, Salisbury, and Endura gloves. The Showa gloves did not provide ample protection to cutting and puncture hazards.

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Manufacture Information• Hook Knives

– R Murphy Hawkbill Knife (UG HAWKC-316D)

– Buckingham (OH Skinning Knife)

• Kevlar Gloves– Youngstown Titan XT

– Salisbury UWG-KLG Kevlar Utility Gloves

– Endura Goat-Grain Driver Gloves with Kevlar Lining

hook knife tip shape / puncture resistant glove … s/2016spring/safety...occupational safety and...

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