WSH Guidelines on Anchorage, Lifelines and Temporary Edge


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Contents

1.

Introduction

2.

Anchors

2.1

Personal Fall Prevention System Attachment

2.2

Types of Anchors

2.2.1

Cast-In

2.2.2

Expanding Socket

2.2.3

Through-type

2.2.4

Chemically Bonded

2.3

Reliability and Strength of Anchors

2.3.1

Obtaining a Safety Factor 2.0

2.3.2

Sharing of Same Anchor

2.4

Anchor Devices

2.5

Anchor Slings

2.6

Correct and Incorrect Anchor Points

2.7

Procurement and Marking Specifications

2.8

Test Certificate after Installation

2.9

Usage and Maintenance of Anchor Devices

3.

Lifelines

3.1

Use of Lifelines at Angles

3.2

Lifelines Conforming to International Standards

3.3

Textile Lifelines

3.3.1

Selection of Textile Lifelines

3.3.2

Knots for Textile Lifelines

3.4

Lifelines Devices

3.5

Vertical Lifelines

3.5.1

Permanent Vertical Lifeline

3.5.2

Temporary Vertical Lifeline

3.6

Vertical Rail

3.7

Vertical Lifeline Materials and Construction

3.7.1

Webbing and Fibre Ropes

3.7.2

Wire Ropes

3.8

Flexible Horizontal Lifeline System

3.9

Flexible Horizontal Lifeline

3.9.1

Wire Rope Lines

3.9.2

Webbing Lines

3.9.3

Fibre Rope Lines

3.10

Minimum Clearance Height for Horizontal Lifelines

3.11

Self-Retracting Lifelines

3.12

Procurement and Selection of Lifelines

3.13

Switching of Lifelines

3.14

Factors Affecting the Conditions of Lifelines

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05 05 05 05 06 06 06 07 07 07 08 12 13 14 15 15
16 16 16 17 17 17 18 20 20 21 22 22 22 23 23 24 24 24 25 25 26 27 28 29
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3.15

Inspection of Lifelines

30

3.16

Flexible Horizontal Lifeline System Marking Specifications

30

4.

Temporary Edge Protection Systems

31

4.1

Criteria in Selecting and Installing a Suitable Temporary Edge

Protection System

32

4.2

Three Classes of Temporary Edge Protection Systems

32

4.2.1

Class A System

32

4.2.2

Class B System

33

4.2.3

Class C System

34

4.3

Materials

35

4.4

Markings

35

4.5

Different Types of Temporary Edge Protections

36

4.5.1

Full Scaffolding

36

4.5.2

Ground Supported Edge Protection

36

4.5.3

Edge Protection Off Structures

37

4.5.4

Parapet Edge Protection

37

4.6

Use of Proprietary Systems

37

5.

Case Application One: Anchorage and Lifelines for ISO Tanks

38

5.1

Accessing top of ISO Tanks Using Ladders

38

5.2

Alternative Access and Fall Prevention Approaches

38

5.2.1

Anchorage and Lifeline Structural Systems

39

5.2.2

Mobile Fall Arrest Anchorage Pole Systems

39

5.2.3

Fall Prevention Systems from top of ISO Tanks

40

5.2.4

Access Structures and Platforms

40

6.

Case Application Two: Anchorage and Lifelines for Formworks

41

6.1

Common Use of Anchors for Formworks

41

6.1.1

Strap Anchors

41

6.1.2

Cast-in Rebar

41

6.1.3

Expandable Bolt Anchor

41

6.2

Work Positioning Device Systems

42

7.

References

43

8.

Acknowledgements

45

Appendix A – Different types of Fall Arrest Systems (with Different Anchorages)

46

Appendix B – Different types of Temporary Edge Protection Systems

47

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1. Introduction
Falls from heights (FFH) is one of the largest causes of death and injury in the workplace. It is therefore essential that measures are taken to protect workers against the risks of falling from heights.
This guide is developed to help employers and workers who are involved in working at heights to better understand the application of anchorage, lifelines and temporary edge protection as a means of fall prevention.
It is important to note that risk assessment needs to be carried out prior to any work at heights (WAH) activities. Whenever possible, eliminate or substitute any WAH activities. Using temporary edge protection systems (such as guardrails) shall be the first option in designing any fall prevention systems. The use of anchorages and lifelines, with proper personal protective equipment (PPE) shall come second if the option of having temporary edge protection is not feasible.
1.1 What this Guide is About
This guide is relevant for WAH activities. It contains salient points on proper application of temporary edge protection to prevent a fall; and correct anchorages and lifelines to arrest a fall during an accident.
This guide also includes two sections of the structural categories (i.e., ISO tanks and formworks) where the understanding of fall preventions systems (such as having correct anchorage and lifelines) can be applied. After reading this guide, the user should be able to: • understand anchors or anchor points and their applications; • understand lifelines and their applications; • understand temporary edge protection systems and their applications; • identify correct applications of anchorages and lifelines for formworks; and • identify correct applications of anchorages and lifelines when working on top of ISO tanks.
1.2 Terms and Definitions
• “Competent person”, refers to a person who has sufficient experience and training to perform the work to be carried out, and has passed such courses as the Commissioner may require for the work.
• An “anchor” is a fixture or place for the secure attachment of lifelines, lifelines or persons. • An “anchor point” (also known as anchorage) is part of an anchor for other equipment in a
personal fall prevention system to be attached to. • An “anchor device” is an element or series of elements of a personal fall prevention system,
which incorporates an anchor point or several anchor points.
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Figure 1: An eyebolt (left) and steel beams are classified as anchors. • A “structural anchor” is an element permanently secured to a structure, to which an anchor
device or equipment for personal fall prevention can be attached. • A “lifeline” is a flexible or rigid line connected at least at one end to a reliable anchor as a
means of fall prevention. • A “lifeline device” (also known as anchor line device) is a device which accompanies the user
along a lifeline. • A “traveller” is a lifeline device which travels in the broadly horizontal plane on a horizontal
lifeline system and is intended to act as mobile anchor points. • A “guided type fall arrester” is a lifeline device with a fall arrest and self-locking function.
It travels along a vertical lifeline without requiring manual adjustment by the user, during upward or downward changes of position.
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2. Anchors
A high proportion of falls in workplaces occur either due to unavailability of proper anchor points or failure of anchors. Therefore, anchors and anchors points must be assessed for suitability and security prior to use.
Personal fall prevention equipment must be anchored securely when in use. Wherever possible, anchor points and anchors should always be positioned above the user. This is to ensure that the lifeline or lanyard is taut or has as little slack as possible. The positioning of anchors and anchor points should not be resting on sharp, rough edges or hot surfaces, as they are likely to be damaged, particularly those made from textiles which would fail under load.
Refer to Appendix A for a list of different types of fall arrest system with different anchorages.
2.1 Personal Fall Prevention System Attachment
The personal fall prevention system may be attached to one of the following: • a permanent structure or suitable features of a building (e.g., a welded eyebolt or a drilled
hole in a steel beam); • an anchor device that is specifically design-made (e.g., an eyebolt installed permanently or
temporarily to a building or structure); or • a feature of the building or structure (e.g., a structural column of which a lanyard, or anchor
sling can be placed around).
2.2 Types of Anchors
There are many types of anchors, some are more suitable for use on certain construction materials than others. Four common types of anchors are listed below.
2.2.1 Cast-in
The anchor (or anchor device) is casted into the surface of the structure as it is being built; hence it is usable for solid concrete structures. This type of anchor requires the use of cross bars positioned perpendicularly behind reinforcing bars (also known as rebars) and a socket positioned behind the cross bar for the insertion of the eyebolt. The life expectancy of this type of anchor should be specified by the manufacturer.
Figure 2: Example of a cast-in eyebolt anchor.
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2.2.2 Expanding Socket
An expanding socket type of anchor makes use of a steel socket which expands upon the installation of the eyebolt and will require drilled holes for installation.

2.2.3 Through-type
Through-type anchors utilise an eyebolt with an extended shank which runs through the material it is installed onto. The eyebolt is then held in place through the use of a back plate and either a locking nut or a threaded bush. Such anchors are ideal for use on thin structural members, such as on steel I-beams. However, these structural members must of sufficient material strength and material to support the anchor loads.

Figure 3: Example of an expanding socket type of eyebolt anchor.

Lockable Nut
Washer

Eyebolt
Load Bearing Structure

2.2.4 Chemically Bonded
Chemically bonded anchors consist of a socket that is held in place by use of a bonding resin. This type of anchor is generally not recommended for use in Singapore, due to the weather and possible reactions between the rainwater and the bonding resin. The manufacturer should specify the products’ applicability in relation to the local climate and life expectancy.

Figure 4: Example of a throughtype anchor.

Knurled socket
Seal

Raisin bond

Eyebolt
Load Bearing Structure

Figure 5: Example of chemically bonded anchor.

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2.3 Reliability and Strength of Anchors
Anchors shall be reliable and have adequate strength and stability to withstand the dynamic and static forces that could be applied to them during a fall scenario.
Anchor devices should conform to SS 570 : 2011 Personal protective equipment for protection against falls from a height – Single point anchor devices and flexible horizontal lifeline systems. A safety factor of 2.0 should be used to calculate the required static strength of an anchor device in a personal fall prevention system. To arrest a fall for a single person use, an anchor device or anchor with a minimum static strength of 12kN (2,697 lbf )1 should be used. For illustration purpose, an anchorage should be able to support an average-size car (with an approximate weight of 1100kg to 1400kg).
Note
1 kN = 1000 N ≈ 100 kgf 12 kN = 12,000 N ≈ 1200 kgf
2.3.1 Obtaining a Safety Factor 2.0
A safety factor of 2.0 can be obtained in one of the recommended ways of using an anchor device by: • re-positioning the anchor device in order to limit the free fall distance; • procuring and using an anchor device with a higher static strength than the minimum
specified; or • incorporating an energy absorber into the personal fall prevention system, such that the
impact force in the event of fall would be limited to 6kN (and this equipment is to be used with an anchor device).
2.3.2 Sharing of Same Anchor
When two or more users are to be connected to a single anchor (either independently or through a shared lifeline), it is important to account for the possibility that they could fall at the same time2.
For two users sharing a single anchor, the minimum breaking strength is 12kN per person (with safety factor of 2.0) in the direction of loading in service. If more than two users are to be connected to the same anchor, the minimum breaking strength of the anchor needs to be increased by 2kN for each additional user.
1For more information on obtaining a safety factor of 2.0, refer to SS570 : 2011 Personal protective equipment for protection against falls from a height – Single point anchor devices and flexible horizontal lifeline systems. 2For more information on sharing of same anchor, refer to BS 8347 : 2005 Code of practice for selection, use and maintenance of personal fall prevention systems and equipment for use in the workplace.
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Thus, in order to maintain a safety factor of 2.0, the minimum static strength of a single anchor for two persons’, three persons’ and four persons’ use should be 24kN; 26kN and 28kN respectively.

Note
1 anchor  1 user  12 kN (with a safety factor 2.0) 1 anchor  2 users  24 kN (with a safety factor 2.0) 1 anchor  3 users  24 kN + 2 kN = 26 kN (with a safety factor 2.0) 1 anchor  4 users  24 kN + 2 kN + 2 kN = 28 kN (with a safety factor 2.0)

It is important to ensure that the design and surveying of the installation of anchors shall be carried out by a competent person.
2.4 Anchor Devices
Table 1 shows the six classes of anchor devices as specified in SS 570 : 2011 Personal protective equipment for protection against falls from a height – Single point anchor devices and flexible horizontal lifeline systems.

Class A1

These are designed to be secured to vertical, inclined and horizontal surfaces. For example, walls, columns and eyebolts.

1

1

Washer

2
Vertical

Inclined

1 2
2
Horizontal
No Items 1 Structural Anchor 2 Anchor Point 1 + 2 = Anchor device

8

Class A2

These are designed to be secured to inclined roofs.

1 2

Inclined Roof
No Items 1 Structural Anchor 2 Anchor Point 1 + 2 = Anchor device

Class B

These are transportable temporary anchor devices. For example, a tripod over a confined space, a beam clamp or an anchor sling.

I-Beam
1

1 Beam Clamp

Tripod No Items 1 Anchor Point
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Class C

These are designed for use with horizontal flexible lifelines.

2

5

3

4

2

1 1

(a) Example of Roof Lifeline Installation

1

4 3

(b) Example of Chimney Lifeline Installation
No Items 1 Structure 2 Extremity Structural Anchor 3 Intermediate Structural Anchor 4 Lifeline 5 Mobile Anchor Point
10

Class D

These are designed for use with horizontal rigid lifelines. For example, rails.

1 2

1 2

Class E

No Items 1 Anchor Rail 2 Mobile Anchor Point
These are dead weight anchors for use on horizontal surfaces.

1

No Items 1 Anchor Point
Note: It is critical to take note that dead weight anchor devices shall not be used where the distance to the edge of the roof is less than 2.5m.
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1
Minimum 2.5m

Limit of distance to roof edge for deadweight anchor devices

Table 1: Classes of anchor devices.
2.5 Anchor Slings
Anchor slings are designed to be wrapped around feature of a structure (e.g., steel beam).
Anchor slings made from textiles (e.g., webbing) should have a minimum breaking strength of 22kN while the minimum breaking strength of anchor slings made from wire rope or chain should be 15kN, in accordance to BS 8347 : 2005 Code of practice for selection, use and maintenance of personal fall prevention systems and equipment for use in the workplace.
Due to the weakening effect, the looping of anchor slings or other lanyards through themselves (known as “lark’s footing or “choking”) should be avoided unless they are designed to allow this.

Figure 6: Example of an anchor sling.

Figure 7: Excessive looping of an anchor sling should be avoided (unless otherwise stated in manufacturer’s manual).
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2.6 Correct and Incorrect Anchor Points
Personal fall prevention systems should not be connected or tied-off to inadequate or improper anchor points. These could fail to provide the intended protection, and may result in fatalities. When assessing by competent person on existing structural features or equipment for used as anchor points, avoid corners or edges that could cut, chafe, or abrade fall prevention components. The following areas should never be used as anchor points unless the minimum structural requirements have being determined to be safe and approved by a competent person: • standard guardrails; • standard or balcony railings; • ladders or rungs; • scaffolding; • light fixtures; • conduit or plumbing; • ductwork or pipe vents; • C-clamps; • wiring harnesses; • rebar (except for positioning during formwork); • another lanyard; • roof stacks, vents, fans or chimney; • TV antennas; and • any point which does not meet the structural requirements.
Figure 8: Fall prevention systems should not be connected directly to portable ladders that are leaned against any structures for the purpose of access. It should be connected to a proper anchorage adjacent to the ladder. A connection to a portable ladder should only be made if the top of the ladder is properly secured and the system tested by a competent person.
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Figure 9: Fall prevention systems should not be connected to any open ended beams or cantilevers, as an initial fall arrest can cause the connection to slip off the open end of the beam or cantilever. Connections to beams and cantilevers should only be made between supports of which the structural strength has been determined and approved by a competent person.
2.7 Procurement and Marking Specifications
Anchors and anchor devices should be acquired through reliable suppliers and be of good construction and manufactured in conformance to recognised international standards . All anchors and anchor devices shall also come with “certified type-examination certificate” or “certificate of conformance” (COC).
Each detachable component of an anchor system or anchor device shall be clearly marked out (using suitable methods not harmful on the material) with the following minimum identification markings: • manufacturer or supplier’s name; • manufacturer showing compliance to international standards • manufacturer or supplier’s trade mark (or any means of original identification); • manufacturer’s batch number or serial number of the component; • manufacturer’s recommended breaking strength (kN) of the anchor; and • manufacturer recommended maximum number of users per anchor.
Markings may also be incorporated in details with a label-tag being tagged along with the anchor devices to show the above intended information.

2.8 Test Certificate after Installation
A test certificate shall be provided by the installer stating that the anchor devices (e.g., eyebolt) have been installed and tested in accordance to SS 570 : 2011 Personal protective equipment for protection against falls from a height – Single point anchor devices and flexible horizontal lifeline systems.
This certificate shall also include a warning against misuse of the anchor device and draw attention to the need to inspect the anchor device before each occasion of use.
2.9 Usage and Maintenance of Anchor Devices
Prior to using anchor devices or systems, they shall be inspected and checked manually in accordance with the manufacturer’s instruction for use.
Each anchor device and anchor system shall be fully examined at least once every year, in accordance with the manufacturer’s instructions, by a competent person authorised by the manufacturer.

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WSH Guidelines on Anchorage, Lifelines and Temporary Edge