LIFTING EQUIPMENT- SWL ESTIMATION OF LOOSE GEAR -CHAIN , PAD EYES CHAIN LING, RINGS , BOW PIECES FOR SWIVELS,HOOKS, SHACKLES, LUGS, RIGGING SCREWS, TURN BUCKLES AND BULL DOG GRIPS, ROUND AND OVAL EYES

All dimensions in MM

CHAIN

RULES OF THUMB :

 ESTIMATED SWL OF CHAIN : (DIAMETER  IN MM - SQUARED) x GRADE  x 0.4

(EXAMPLE : WLL of grade 80 high tensile chain 10 mm = 10 x 10 x 80 x 0.4= 3,200 kg WLL.)

MAXIMUM PERMISSIBLE WEAR INCLUDING PITTING WEAR : 10% REDUCTION IN DIAMETER OF CROSS SECTION AT ANY POINT

WEAR POINTS IN A CHAIN : 

Links will wear at the link ends from metal wear down. 

Links will wear on the outer sides of the link from being dragged

SMALLEST CHAIN DIAMETER FOR LIFTING:

GRADE 30 (BASIC GRADE)          : 8.0 MM

HT GRADE 80 CHAIN                    : 5.5 MM

MAXIMUM WORKING TEMPERATURE 

GRADE 30 (BASIC GRADE)          :  260 DEGREES CENT

HT GRADE 80 CHAIN                    : 400 DEGREES CENT

IF TEMPERATURE EXCEEDS 260 DEGREES CENT- WLL OF CHAIN GETS DRASTICALLY REDUCED.

MARKINGS INDICATE- IF THE CHAIN IS FOR LIFTING AND ALSO THE GRADE- MOST CHAINS ARE MARKED AT EVERY 20 TH LINK OR A DISTANCE OF 1 METER.

IF CHAIN HAS NO WLL TAG :

*DISCARD THE SAME FROM SERVICE TILL CHECKED PROPERLY --IF IT HAS NO TAG AND GRADE MARKING

*CHECK GRADE MARKINGS AND USE ACCORDINGLY TILL NEW TAG IS MARKED

*IF UNSURE ABOUT MARKINGS , TREAT IT AS GRADE 30 CHAIN  FOR USE- PROVIDED CONDITION IS GOOD UNTIL PROPERLY CHECKED .

DEFECTS IN CHAIN MAKING IT UNFIT FOR USE:

1.Twisted, kinked, knotted. 

2.Stretched, locked or does not move freely. 

3.Gouged, cut or crushed more than 10% of the link's original diameter. 

4.Pitting more than 10% wear in the diameter of the link. 

5.Exposed to excessive heat. 

6.Cracked, spot welded. 

PAD EYES

CHAIL LINK , RINGS , BOW PIECES FOR SWIVELS

Minimum tensile strength of material,		Value of c
in N/mm2	Links		Rings
430	0,0053		0,0116
540	0,0071		0,0155

Swivels are to be fitted with plain bearings or with ball or roller thrust bearings

Dimensions of bow pieces for swivels(in MM)

Safe working load, in tonnes	a                        b            d1            d2	e
1,0	37                    64              13          20	20
1,6	46                    80              16          25	25
2,0	53                    92              18          25	29
2,5	60                  104             21          30	32
3,2	67                  116             23          30	36
4,0	74                  128             26          35	40
5,0	83                  144             29          40	45
6,3	92                  160             32          40	50
8,0	104                180             36          45	56
10,0	117                204             41          55	64
12,5	131                228             46          60	71

HOOKS

The safe working load of a hook is the maximum load that the hook is certified to lift in service.
-Hooks may be of the ‘C’ or Liverpool type or of the double armed Ramshorn type, as indicated 
- ‘C’ type hooks are not to be used for safe working loads exceeding 25 t.

-Hooks may be of killed mild steel or higher tensile steel. After forging, mild steel hooks are to be normalised and higher tensile steel hooks subjected to a suitable heat treatment.

‘C’ type hooks are to be so designed as to reduce as far as possible the risk of the hook catching on an obstruction when hoisting and also the risk of the displacement of the load.

**Where the hook is not manufactured in accordance with a recognised standard, the safe working load may be taken as:
                             SWL = ck (H – 0,1D)2 tonnes
where the dimensions are measured in millimetres 
 The values of c and k are to be obtained 

Values of c for hooks(INTERMEDIATE VALUES OBTAINED BY INTERPOLATION)

Minimum tensile                                      c strength of steel,

in N/mm²                     'C' hooks            Ramshorn hooks

430                         0,0011                          0,0016

540                         0,0015                          0,0021

Values of k for hooks

M					q
H	40°	30°	25°	20°	15°	10°	5°	0°
0,55	0,48	0,75	0,85	0,92	0,98	1,03	1,06	1,10
0,65	0,82	1,01	1,08	1,12	1,16	1,20	1,23	1,27
0,75	1,07	1,18	1,22	1,27	1,30	1,34	1,37	1,40
0,85	1,16	1,30	1,33	1,36	1,40

The shank is to be such that the direct tensile stress complies with Table below. Detail design at the end of the threaded section is to be such as to minimise stress concentrations.

   Dimensions of higher tensile steel 'C' hooks

Safe working load, in tonnes	a	b	c	D	H	M	G
1,0	124	78	6	31	26	17	17
1,6	156	98	8	39	33	21	20
2,0	176	110	8	44	37	24	25
2,5	196	123	10	49	41	27	25
3,2	219	138	12	55	46	30	30
4,0	247	156	12	62	52	34	30
5,0	279	176	14	70	59	38	35
6,3	311	196	16	78	66	43	40
8,0	351	221	18	88	74	48	45
10,0	391	246	20	98	82	54	50
12,5	439	276	22	110	92	60	55
16,0	495	311	24	124	104	68	60
20,0	555	349	28	139	117	76	70
25,0	622	392	32	156	131	86	80
NOTES
1.       All dimensions are given in millimetres and are illustrated
2.       Minimum material tensile strength  540 N/mm2.

          Dimensions of higher tensile steel Ramshorn hooks

Safe working load, in tonnes	a	b	c	D	H	M	G
20	238	457	30	121	113	76	89
25	267	511	33	133	126	86	102
32	299	567	37	146	143	97	114
40	329	616	41	162	155	108	127
50	365	683	46	178	174	117	140
63	408	745	51	194	195	132	144
80	452	813	57	213	216	146	152
100	498	883	64	229	241	162	165
NOTES
1.       All dimensions are given in millimetres and are illustrated
2.       Minimum material tensile strength  540 N/mm2.

SHACKLES

Shackles should be inspected for:
(a) Mechanical damage to pin or body;
(b) Correct tensile pin fitted;
(c) Correct pin length; and

(d) Wear.

Mild steel shackles are to be normalised after forging and before tapping and screwing. Higher tensile and alloy steel shackles are to be subjected to a suitable heat treatment.

Safety factor: 6 times SWL = minimum breaking strength

Dimensions of Dee shackles

Safe working load, in tonnes	a	b	d1	Mild steel d2	d1	Higher tensile steel d2
1,0	20	44	13	15	11	12
1,6	25	55	17	19	13	15
2,0	28	62	19	21	15	17
2,5	31	69	21	24	17	19
3,2	35	78	24	27	19	21
4,0	40	87	26	30	21	23
5,0	44	97	29	33	23	26
6,3	50	109	33	37	26	29
8,0	56	123	37	42	29	33
10,0	63	138	41	47	33	37
12,5	70	154	46	53	36	42
16,0	79	174	52	60	41	47
20,0	89	195	59	67	46	52
25,0	99	218	65	75	51	59
32,0	112	247	74	84	58	66
40,0	125	275	83	94	65	74
50,0	140	308	92	106	72	83
63,0	157	346	104	119	81	93
80,0	177	390	117	134	91	105

Dimensions of Bow shackles

Safe working load, in tonnes	a	b	2r	d1	Mild steel d2	Higher tensile steel d1                                     d2
1,0	20	50	34	14	16	12	13
1,6	25	63	43	18	20	15	16
2,0	28	70	48	20	22	17	18
2,5	31	78	53	23	25	18	20
3,2	35	89	60	25	28	21	22
4,0	40	99	67	28	31	23	25
5,0	44	111	75	32	35	26	28
6,3	50	124	84	36	39	29	32
8,0	56	140	95	40	44	33	36
10,0	63	157	106	45	49	36	40
12,5	70	175	119	50	55	41	44
16,0	79	198	135	56	62	46	50
20,0	89	221	150	63	69	51	56
25,0	99	248	168	70	77	57	63
32,0	112	280	190	80	87	65	71
40,0	125	313	213	89	98	72	79
50,0	140	350	248	99	109	81	89
63,0	157	394	267	112	123	91	100
80,0	177	444	301	126	138	102	112

LUGS

Dimensions of lug fittings

Safe working load, in tonnes	Shank d1	a	b	d2	d3
1,0	M18	19	8	17	35
1,6	M22	23	11	21	45
2,0	M24	26	12	23	50
2,5	M27	29	13	25	55
3,2	M30	32	14	28	60
4,0	M33	35	15	31	65
5,0	M36	39	18	37	75
6,3	M42	45	20	40	85
8,0	M45	49	23	46	95
10,0	M52	58	26	50	110
12,5	M56	64	28	54	120
16,0	M64	70	30	62	130
20,0	M72 x 6	74	33	70	140
25,0	M76 x 6	80	35	74	150
32,0	M80 x 6	90	40	82	170

RIGGING SCREWS AND TURNBUCKLES

Rigging screws and turnbuckles should be inspected for:

(a) Thread damage and thread engaged to full length of threaded body;

(b) Deformation; and

(c) Corrosion.

Thread Diameter (A)	Safe Working Load (SWL)	Thread Diameter (A)	Safe Working Load (SWL)
mm	tonnes	mm	tonnes
8	0.2	39	6.0
10	0.3	42	7.5
12	0.5	48	10.0
16	0.75	56	15.0
20	1.25	64	20.0
22	2.0	72	25.0
27	3.0	76	30.0
30	4.0	85	40.0
33	5.0	100	50.0

BULL DOG GRIPS

Size Nominal Diameter mm	Required Number of Wire Rope Grips to Attain 85% of Rope Minimum Breaking Load	Required Tightening Torque to Obtain Required Efficiency Newton metres
5.0	3.0	2.0
6.5	3.0	3.5
8.0	4.0	6.0
10.0	4.0	9.0
13.0	4.0	33.0
16.0	4.0	49.0
19.0	4.0	68.0
22.0	5.0	107.0
26.0	5.0	147.0
30.0	6.0	212.0
34.0	6.0	296.0
40.0	6.0	363.0

ROUND AND OVAL EYES

Safe working load, in tonnes	Shank d1	Round d2	d3	b	g	Oval d4	e
1,0	M18	11	24	48	21	12	14
1,6	M22	14	30	58	26	16	18
2,0	M24	16	34	58	26	16	18
2,5	M27	18	39	72	32	21	23
3,2	M30	20	44	72	32	21	23
4,0	M33	22	48	94	40	26	28
5,0	M36	25	54	94	40	26	28
6,3	M42	27	60	108	45	29	32
8,0	M45	31	68	115	49	32	35
10,0	M52	35	76	125	54	36	39
12,5	M56	39	86	144	60	41	44
16,0	M64			163	66	46	49
20,0	M72 x 6			173	72	56	54
25,0	M76 x 6			192	80	56	59
32,0	M80 x 6			216	90	60	64
40,0	M90 x 6			240	100	66	70
50,0	M100 x 6			264	110	74	78
63,0	M110 x 6			290	120	84	89
80,0	M120 x 6			325	135	94	99
100,0	M130 x 6			360	150	105	111