Currency
June 29, 2019
A harness is the means by which the user is safely connected to the rest of a fall protection system when working at height or near an edge where the potential for a fall exists. These systems can be thought of as a chain, with the anchor point at one end, a number of links in between, and the harness at the other end.
There are many different kinds of safety measures which may be in place to keep workers at height safe, and any system requiring Personal Protection Equipment (PPE) will require a harness of some sort to be worn by the worker.
The harness plays a vital role in preventing the user from hitting the ground if an accident were to occur, and it is the harness to which all other elements of the system such as lanyards and shock absorbers must be attached. Harness types All harnesses fulfil one basic requirement: to connect a user to a system, normally for either fall arrest, work positioning, restraint or rescue purposes. There are a number of different types of harness available for each of these purposes.
At its most basic a harness will have at least one attachment point, for connection to a system, and will fit securely to the user. Harnesses can be “full-body”, with straps in the shoulder and thigh areas, and sometimes a waist belt; or they may cover only the lower half of the body (not to be used for fall arrest), consisting of a waist belt and thigh straps only. Full body harnesses are likely to be worn by construction workers or service personnel, where their work may require them to interact with and connect to a variety of safety systems, whereas lower body harnesses may be worn by arborists or recreational climbers who require greater freedom of movement when climbing.
Attachment points for fall arrest are commonly located in the dorsal area of the harness, and the chest or sternum area.
As well as having attachment points for fall arrest, harnesses may also have attachment points for work positioning or restraint lanyards – lanyards that limit the worker’s distance from an anchor point, or that wrap around some part of the user’s work area to keep them in place whilst they work. These points are usually located at the hips, and the back of the waist belt. Separate attachment points may also be provided to attach tools, or to “park” lanyards or other accessories when not in use, to prevent them becoming tangled with the wearer during use.
For workers operating in confined areas, such as down manholes, or for marine applications where movement on and off vessels may be facilitated by means of overhead winches, an additional “rescue” attachment point may be provided. This usually consist of attachments on each shoulder of the harness that are connected together over the wearer’s head to the winch or rescue mechanism.
Harnesses may be provided with a sit attachment – a connection point at the front of the waist belt that when fixed to a suitable lanyard, allows the user to lean back into a comfortable sitting position whilst working at height. All harnesses must keep a user safe, either in the event of a fall or keep them in the correct position to prevent a fall, and so the choice of harness and attachment point must be considered for each application.
Harnesses for use in specialised environments are also produced; for example, marine or diving harnesses, as well as harnesses for firefighters and armed forces personnel. These have their own specific requirements in addition to the general safety requirements of harnesses.
There are a number of standards that specify the testing and performance requirements for harnesses.
The tests described in this standard must be carried out on each fall arrest attachment point on the harness, to ensure that each is fit for purpose and that the harness performs safely whichever point is used, dorsal, sternal or shoulder attachments.
In addition to a design assessment, harnesses are subject to a dynamic drop test designed to simulate a worst-case fall scenario.
The harness is fitted to a standard European fall-arrest torso dummy weighing 100kg, and connected to a suitable anchor via a 2m lanyard, made from 11mm dynamic mountaineering rope, and tied with bowline knots at either end. The dummy is then subjected to two, 4m free fall drops: once in a legs-first orientation, and once in a head-first orientation. Some adjustment of the harness between drops is allowed, but the same lanyard is used, and the second drop must be carried out within 15 minutes of the first drop.
The harness must arrest the dummy’s fall and must maintain it in an upright position after the drop – within 50° of vertical.
Each attachment point must also pass two static tests, where loads of 15kN and 10kN are applied in an upwards (towards the neck) and downwards (towards the floor) direction respectively. The harness must withstand these two tests for three minutes without releasing the torso dummy.
In addition, any metallic elements of the harness must be tested for their resistance to corrosion, which is done by subjecting them to 24 hours in a salt corrosion machine in accordance with ISO 9227:2017.
This standard is used to test the waist belt attachment points which could be a separate belt or integrated into a full body harness. Similar to EN361 in its scope, this standard requires the harness to withstand a 1m dynamic drop when attached to one of the waist attachment points via a 1m lanyard.
For the static testing, the harness is fitted to a metal cylinder, rather than the waist area of the dummy, and a static force of 15kN applied between the cylinder and the attachment point. Static loads are applied for three minutes. Metallic elements are also subjected to the same corrosion test as in EN 361:2002 but for 48 hours.
This standard is used to test the sit attachment point of a full body harness or the attachment of a lower body harness. One of the most important parts of the testing for this standard is an ergonomic assessment. Two wearers, meeting height and weight requirements, take it in turns to don the harness and are then suspended from the sit attachment point for just under four minutes. During this time they are asked a number of questions about their comfort, to establish that the harness is fit for purpose.
Testing the attachment point on the front of the waist belt, the harness is then required to withstand a 2m dynamic drop test on a 1m lanyard. Although the standard 100kg torso dummy is normally used, if the manufacturer claims a maximum user weight greater than 100kg, then this larger mass should be used for the dynamic drops.
A static test of at least 15kN (or ten times the maximum user weight) is also required, with the torso dummy anchored to the floor and the force applied upwards from the sit attachment point.
Metallic elements are also subjected to the same corrosion test as in EN 361:2002, however the exposure time is increased to 48 hours with an hour break half way through. EN 1497:2007 Rescue harnesses This standard is used to test the rescue attachment points of a full body harness which could be specifically for rescue only or integrated into a harness for fall arrest. The testing requirements for harnesses claiming conformance to EN 1497 are very similar to those outlined in EN 361, with the addition of an ergonomic assessment, similar to that required for EN 813. Two ergonomic subjects are suspended in turn from the overhead rescue attachment points, and their opinion on the comfort of the harness is sought by means of a questionnaire.
Dynamically, the harness is expected to withstand two 1m drops on a 2m lanyard, one after the other. As with EN 813, these tests are to be carried out on a dummy with mass equal to that of the maximum user weight.
Afterwards a static test at 15kN, or ten times the maximum user weight is to be carried out.
Metallic elements are also subjected to the same corrosion test as in EN 361:2002, however the exposure time is increased to 48 hours with an hour break half way through.
This standard is used to test harness specifically for mountaineering and consists of four types: adult full body harness (type A); child’s full body harness (type B); chest harness only (type C); lower harness (type D). If a type A harness can be split into a type C and D, then it must meet all requirements together and separately. The torso dummy on which the testing for this standard is to be carried out differs in shape and form from the torso dummy in EN 361: 2002, in that it is considerably more contoured, and has a more well-defined waist area.
After a lengthy period of conditioning, during which the samples are dried at 50°C before being stored at 23°C and 50% rh, the harnesses are subject to a number of static tests. This standard does not incorporate any dynamic or drop tests.
There are different requirements for each type of harness. Types A and B are tested on the torso dummy, whilst C type (waist belts) are tested on a metal cylinder. An initial static load of 800N is applied to the relevant attachment point (300N for type C), and the positions of buckles or other adjustment devices are noted before the load is increased to 15kN with the dummy in a head up orientation, and 10kN with the dummy in a head down orientation. Any damage to the harness is noted, as is any slippage of the adjustment devices.
For all of the European standards mentioned above, a Notified Body (NB) would require a product to meet all the relevant standards before an EU type examination certificate can be issued, allowing the CE mark to be applied and sale into Europe. Fall protection is considered Category III under the European PPE Regulation 2016/425 and therefore is also subject to ongoing conformity assessment by a Notified Body.
This standard incorporates testing of the majority of attachment points possible on harness into one document. All applicable clauses are required to undergo qualification (triplicate) testing before a product can be marked as compliant and verification testing at suitable intervals. Testing is carried out on an ANSI torso dummy which weighs 100kg and which is contoured with shoulders and defined bands and areas on the torso in which certain straps should sit when the harness is fitted. Instead of using a disposable rope lanyard, this standard requires a wire lanyard, terminated with swaged loop ends.
For the dynamic testing required for this standard, rather than specifying a set freefall height for the drop, there is a force requirement. A load cell is positioned between the anchor point and the test lanyard, and this records force during the drop. The force should be 16kN. Any pass result where the force was under 16.0kN must be discounted as invalid, and failure above 17.7kN is also invalid.
Dorsal and sternal fall arrest attachment points are to be dynamically tested in this manner.
During the test, at least one of the fall arrest visual indicators fitted to the harness must permanently deploy, and after testing the torso dummy must remain safely suspended in the harness for five minutes. The final height of the dummy after this fiveminute suspension is also recorded, and is then subtracted from its starting position in order to establish the degree of stretch/elongation in the harness. As in EN361, the angle of the torso dummy at rest is important and must not exceed 30° from vertical.
A static test must also be carried out on these attachment points, applying a force of 16kN for one minute. There must be no tearing of straps, and slippage through buckles must be less than 25mm.
Lanyard parking attachment points should be so designed that if a lanyard clipped to them is caught on something, the lanyard attachment point itself should break to minimise the risk of entanglement. Correspondingly, a static test on each lanyard parking attachment point is carried out to establish its breaking strength, which must be no more than 0.5kN.
Shoulder attachments for rescue and retrieval purposes, waist rear attachments for work restraint and hip attachments to be used as a pair for work positioning all need to be tested with a static test of 16kN for one minute, without tearing, and with a maximum slippage through adjustment buckles of 25mm.
This standard is the Australian/New Zealand equivalent of the European standards EN 361: 2002, EN 358: 1999 and EN 813: 2008 with a few key differences. For the fall arrest attachment points the dynamic test is carried out using the same test dummy as in EN 361 which is dropped feet first, followed by head first on the same harness. The difference is the 12mm diameter three-strand polyester hawser-laid reference lanyard.
The dynamic testing on the waist belt attachment is also different in that the test is done using a work positioning lanyard as specified by the manufacturer, attached to both points and wrapped around the anchorage point. This way both are tested together to show compatibility in the event of a shock load.
The other main difference in this standard is that all webbing shall be tested for UV degradation. This involves static strength testing to breaking point of new webbing and UV exposed webbing to see how the exposure has affected the overall strength. The UV samples should retain at least 70% of the breaking strength that the unexposed samples demonstrated.
There are many different kinds of safety measures which may be in place to keep workers at height safe, and any system requiring Personal Protection Equipment (PPE) will require a harness of some sort to be worn by the worker.
The harness plays a vital role in preventing the user from hitting the ground if an accident were to occur, and it is the harness to which all other elements of the system such as lanyards and shock absorbers must be attached. Harness types All harnesses fulfil one basic requirement: to connect a user to a system, normally for either fall arrest, work positioning, restraint or rescue purposes. There are a number of different types of harness available for each of these purposes.
At its most basic a harness will have at least one attachment point, for connection to a system, and will fit securely to the user. Harnesses can be “full-body”, with straps in the shoulder and thigh areas, and sometimes a waist belt; or they may cover only the lower half of the body (not to be used for fall arrest), consisting of a waist belt and thigh straps only. Full body harnesses are likely to be worn by construction workers or service personnel, where their work may require them to interact with and connect to a variety of safety systems, whereas lower body harnesses may be worn by arborists or recreational climbers who require greater freedom of movement when climbing.
Attachment points for fall arrest are commonly located in the dorsal area of the harness, and the chest or sternum area.
As well as having attachment points for fall arrest, harnesses may also have attachment points for work positioning or restraint lanyards – lanyards that limit the worker’s distance from an anchor point, or that wrap around some part of the user’s work area to keep them in place whilst they work. These points are usually located at the hips, and the back of the waist belt. Separate attachment points may also be provided to attach tools, or to “park” lanyards or other accessories when not in use, to prevent them becoming tangled with the wearer during use.
For workers operating in confined areas, such as down manholes, or for marine applications where movement on and off vessels may be facilitated by means of overhead winches, an additional “rescue” attachment point may be provided. This usually consist of attachments on each shoulder of the harness that are connected together over the wearer’s head to the winch or rescue mechanism.
Harnesses may be provided with a sit attachment – a connection point at the front of the waist belt that when fixed to a suitable lanyard, allows the user to lean back into a comfortable sitting position whilst working at height. All harnesses must keep a user safe, either in the event of a fall or keep them in the correct position to prevent a fall, and so the choice of harness and attachment point must be considered for each application.
Harnesses for use in specialised environments are also produced; for example, marine or diving harnesses, as well as harnesses for firefighters and armed forces personnel. These have their own specific requirements in addition to the general safety requirements of harnesses.
Testing harnesses
There are a number of standards that specify the testing and performance requirements for harnesses.
EN 361:2002 Full body harnesses
The tests described in this standard must be carried out on each fall arrest attachment point on the harness, to ensure that each is fit for purpose and that the harness performs safely whichever point is used, dorsal, sternal or shoulder attachments.
In addition to a design assessment, harnesses are subject to a dynamic drop test designed to simulate a worst-case fall scenario.
The harness is fitted to a standard European fall-arrest torso dummy weighing 100kg, and connected to a suitable anchor via a 2m lanyard, made from 11mm dynamic mountaineering rope, and tied with bowline knots at either end. The dummy is then subjected to two, 4m free fall drops: once in a legs-first orientation, and once in a head-first orientation. Some adjustment of the harness between drops is allowed, but the same lanyard is used, and the second drop must be carried out within 15 minutes of the first drop.
The harness must arrest the dummy’s fall and must maintain it in an upright position after the drop – within 50° of vertical.
Each attachment point must also pass two static tests, where loads of 15kN and 10kN are applied in an upwards (towards the neck) and downwards (towards the floor) direction respectively. The harness must withstand these two tests for three minutes without releasing the torso dummy.
In addition, any metallic elements of the harness must be tested for their resistance to corrosion, which is done by subjecting them to 24 hours in a salt corrosion machine in accordance with ISO 9227:2017.
Positioning or Restraint
This standard is used to test the waist belt attachment points which could be a separate belt or integrated into a full body harness. Similar to EN361 in its scope, this standard requires the harness to withstand a 1m dynamic drop when attached to one of the waist attachment points via a 1m lanyard.
For the static testing, the harness is fitted to a metal cylinder, rather than the waist area of the dummy, and a static force of 15kN applied between the cylinder and the attachment point. Static loads are applied for three minutes. Metallic elements are also subjected to the same corrosion test as in EN 361:2002 but for 48 hours.
EN 813:2008 Sit harnesses
This standard is used to test the sit attachment point of a full body harness or the attachment of a lower body harness. One of the most important parts of the testing for this standard is an ergonomic assessment. Two wearers, meeting height and weight requirements, take it in turns to don the harness and are then suspended from the sit attachment point for just under four minutes. During this time they are asked a number of questions about their comfort, to establish that the harness is fit for purpose.
Testing the attachment point on the front of the waist belt, the harness is then required to withstand a 2m dynamic drop test on a 1m lanyard. Although the standard 100kg torso dummy is normally used, if the manufacturer claims a maximum user weight greater than 100kg, then this larger mass should be used for the dynamic drops.
A static test of at least 15kN (or ten times the maximum user weight) is also required, with the torso dummy anchored to the floor and the force applied upwards from the sit attachment point.
Metallic elements are also subjected to the same corrosion test as in EN 361:2002, however the exposure time is increased to 48 hours with an hour break half way through. EN 1497:2007 Rescue harnesses This standard is used to test the rescue attachment points of a full body harness which could be specifically for rescue only or integrated into a harness for fall arrest. The testing requirements for harnesses claiming conformance to EN 1497 are very similar to those outlined in EN 361, with the addition of an ergonomic assessment, similar to that required for EN 813. Two ergonomic subjects are suspended in turn from the overhead rescue attachment points, and their opinion on the comfort of the harness is sought by means of a questionnaire.
Dynamically, the harness is expected to withstand two 1m drops on a 2m lanyard, one after the other. As with EN 813, these tests are to be carried out on a dummy with mass equal to that of the maximum user weight.
Afterwards a static test at 15kN, or ten times the maximum user weight is to be carried out.
Metallic elements are also subjected to the same corrosion test as in EN 361:2002, however the exposure time is increased to 48 hours with an hour break half way through.
EN 12277:2015 Mountaineering harnesses
This standard is used to test harness specifically for mountaineering and consists of four types: adult full body harness (type A); child’s full body harness (type B); chest harness only (type C); lower harness (type D). If a type A harness can be split into a type C and D, then it must meet all requirements together and separately. The torso dummy on which the testing for this standard is to be carried out differs in shape and form from the torso dummy in EN 361: 2002, in that it is considerably more contoured, and has a more well-defined waist area.
After a lengthy period of conditioning, during which the samples are dried at 50°C before being stored at 23°C and 50% rh, the harnesses are subject to a number of static tests. This standard does not incorporate any dynamic or drop tests.
There are different requirements for each type of harness. Types A and B are tested on the torso dummy, whilst C type (waist belts) are tested on a metal cylinder. An initial static load of 800N is applied to the relevant attachment point (300N for type C), and the positions of buckles or other adjustment devices are noted before the load is increased to 15kN with the dummy in a head up orientation, and 10kN with the dummy in a head down orientation. Any damage to the harness is noted, as is any slippage of the adjustment devices.
For all of the European standards mentioned above, a Notified Body (NB) would require a product to meet all the relevant standards before an EU type examination certificate can be issued, allowing the CE mark to be applied and sale into Europe. Fall protection is considered Category III under the European PPE Regulation 2016/425 and therefore is also subject to ongoing conformity assessment by a Notified Body.
ANSI Z359.11-2014 Full body harnesses
This standard incorporates testing of the majority of attachment points possible on harness into one document. All applicable clauses are required to undergo qualification (triplicate) testing before a product can be marked as compliant and verification testing at suitable intervals. Testing is carried out on an ANSI torso dummy which weighs 100kg and which is contoured with shoulders and defined bands and areas on the torso in which certain straps should sit when the harness is fitted. Instead of using a disposable rope lanyard, this standard requires a wire lanyard, terminated with swaged loop ends.
For the dynamic testing required for this standard, rather than specifying a set freefall height for the drop, there is a force requirement. A load cell is positioned between the anchor point and the test lanyard, and this records force during the drop. The force should be 16kN. Any pass result where the force was under 16.0kN must be discounted as invalid, and failure above 17.7kN is also invalid.
Dorsal and sternal fall arrest attachment points are to be dynamically tested in this manner.
During the test, at least one of the fall arrest visual indicators fitted to the harness must permanently deploy, and after testing the torso dummy must remain safely suspended in the harness for five minutes. The final height of the dummy after this fiveminute suspension is also recorded, and is then subtracted from its starting position in order to establish the degree of stretch/elongation in the harness. As in EN361, the angle of the torso dummy at rest is important and must not exceed 30° from vertical.
A static test must also be carried out on these attachment points, applying a force of 16kN for one minute. There must be no tearing of straps, and slippage through buckles must be less than 25mm.
Lanyard parking attachment points should be so designed that if a lanyard clipped to them is caught on something, the lanyard attachment point itself should break to minimise the risk of entanglement. Correspondingly, a static test on each lanyard parking attachment point is carried out to establish its breaking strength, which must be no more than 0.5kN.
Shoulder attachments for rescue and retrieval purposes, waist rear attachments for work restraint and hip attachments to be used as a pair for work positioning all need to be tested with a static test of 16kN for one minute, without tearing, and with a maximum slippage through adjustment buckles of 25mm.
AS/NZS 1891.1
This standard is the Australian/New Zealand equivalent of the European standards EN 361: 2002, EN 358: 1999 and EN 813: 2008 with a few key differences. For the fall arrest attachment points the dynamic test is carried out using the same test dummy as in EN 361 which is dropped feet first, followed by head first on the same harness. The difference is the 12mm diameter three-strand polyester hawser-laid reference lanyard.
The dynamic testing on the waist belt attachment is also different in that the test is done using a work positioning lanyard as specified by the manufacturer, attached to both points and wrapped around the anchorage point. This way both are tested together to show compatibility in the event of a shock load.
The other main difference in this standard is that all webbing shall be tested for UV degradation. This involves static strength testing to breaking point of new webbing and UV exposed webbing to see how the exposure has affected the overall strength. The UV samples should retain at least 70% of the breaking strength that the unexposed samples demonstrated.
SOURCE:
https://www.hsimagazine.com/article/harnessing-safety
Recent Posts
Popular Posts
