Debswana Spec 373001

DS SPEC 373001

Document status Approved Copyright

ISSUE 0 15 October 2004 Page 1 of 10

Debswana Specification Conveyors: Specification Requirements for Belt Conveyor Idlers and Rolls

DS SPEC 373001



1 SCOPE 3

2 TECHNICAL REQUIREMENTS TO BE SPECIFIED BY THE ENGINEER 3

3 DEFINITIONS 3

4 REQUIREMENTS 3 4.1 GENERAL 3 4.2 ROLLS 4 4.3 BEARING ASSEMBLY 5 4.4 IDLERS 6 4.5 CORROSION PROTECTION - MOUNTING BRACKETS 7 5 QUALITY ASSURANCE PROVISIONS 8 5.1 QUALITY MANAGEMENT REQUIREMENTS 8 5.2 DRAWINGS 8 5.3 DESIGN CALCULATIONS 8 5.4 SAMPLING FOR INSPECTION AND TEST 8 5.5 GUARANTEE 8 6 TEST AND INSPECTION METHODS 8

7 MARKING AND PACKING 8 7.1 MARKING 8 7.2 PACKING 8 APPENDIX A: RELATED DOCUMENTS 9

APPENDIX B: RECORD OF AMENDMENTS 9

APPENDIX C: RELATED CALCULATIONS 10

DS SPEC 373001



1 SCOPE

This specification details the additions and exceptions to requirements for idlers and rolls complying with SANS 1313 for general-purpose belt conveyor systems. This specification shall be read in conjunction with SANS 1313.

2 TECHNICAL REQUIREMENTS TO BE SPECIFIED BY THE ENGINEER

The following requirements shall be specified on every invitation to tender, contract or order:

• Title, reference number, date and issue of this specification

• Nominal width of belt to be carried

• Number and type of idler(s) (see Clause 4.4)

• Drop height of return idler(s) (see Clause 4.4.4)

• Whether tilted outer inclined rolls are required (see Clause 4.4.8)

• Debswana stock code

• The series (see Clause 4.4.3)

• The colour of the final paint topcoat (see Clause 4.5)

3 DEFINITIONS

For the purpose of this specification the definitions contained in SANS 1313 and the following shall apply:

APPROVED : Approved by the Engineer in writing

ENGINEER : The Consulting Mechanical and Electrical Engineer, or his technical representative appointed in writing

SANS : South African National Standards

DS : Debswana Specification

The following terms are defined in the General Conditions of Contract:

• Debswana, Company, Contractor.

4 REQUIREMENTS

4.1 GENERAL

Unless otherwise specified the dimensions and construction of idlers and rolls shall be in accordance with the requirements of SANS 1313.

DS SPEC 373001



4.2 ROLLS

4.2.1 Rolls supplied in accordance with this specification shall have shafts with closed ends and without end caps.

4.2.2 Design: component parts of rolls including fabrication, seals, lubrication and assembly shall be designed for a basic life rating of not less than 75 000 hours.

4.2.3 Roll material: rolls shall be manufactured from steel tube complying with the requirements of SANS 657 Part III or from spun grey cast iron complying with the requirements of SANS 1034 grade 300.

4.2.4 Roll ends: roll ends shall be simultaneously machined to accept the bearing housings and shall be chamfered 1.5mm at 45°.

4.2.5 Roll diameter: nominal roll diameter shall be as follows:

• Troughing : 125mm

• Impact : 150mm

• Return : 125mm

4.2.6 Shaft material: shafts shall be manufactured from steel complying with the requirements of BS 970 part 1 Grade 070M20.

4.2.7 Shaft tolerances: shaft ends shall be to the tolerances recommended by the bearing manufacturer and to a surface finish not rougher than 3.2mm in accordance with the requirements of the Ra series of BS 1134.

4.2.8 Bearing housings: shall be accurately aligned in relation to each other and the bearing assembly. Tolerances for fitting the bearing shall be as recommended by the bearing manufacturer.

4.2.9 Bearing location: the inner race of each bearing shall be positively located on the shaft on at least one side by an approved means.

4.2.10 Peripheral runout of rolls (TIR): the total indicator reading of the perimeter of a roll shall not exceed the value calculated as follows:

Centre of the roll TIR = 600L

+ 0.55mm

Outer edge of the roll TIR = 0.5 mm

where L = roll length, mm

DS SPEC 373001



4.3 BEARING ASSEMBLY

4.3.1 Bearing type: bearings fitted to rolls shall be one of the following types:

Rigid deep groove ball bearings complying with the requirements of ISO 15 series 62.

Seize resistance cage bearing type SKF BBIB 420 or suitable approved equivalent.

Spherical roller bearings complying with the requirements of ISO 15 series 222.

Spherical roller bearings shall be fitted to all impact rolls.

4.3.2 Bearing Static Load: bearings fitted to troughing and impact rolls shall be capable of carrying the following minimum static loads:

• Rigid deep groove ball bearings : 96kg

• Seize resistant cage bearings : 86kg

• Spherical roller bearings : 245kg

4.3.3 Basic Rating Life: basic rating life (L10h) as defined in BS 5512 for each bearing shall not be less than 75 000 hours for a bearing load as specified in Clause 4.3.2.

4.3.4 Misalignment: caused by roller shaft deflection shall not exceed the following when calculated as detailed in Appendix C, C1.1.

• Rigid deep groove ball bearing : 0° 6'

• Seize resistant cage bearing : 0° 14'

• Spherical roller bearing : 1° 30'

4.3.5 Seals: bearing seals shall incorporate the following. Alternatives shall be approved:

4.3.5.1 Inner lip seal: shall prevent contamination from inside the roll and loss of grease from the bearing.

4.3.5.2 Bearing outer seal: shall be of the multiple labyrinth type. Minimum length of the effective sealing passage shall be 18mm.

4.3.5.3 Outer cover: shall assist grease retention and prevent ingress of dirt or water.

4.3.6 Lubrication: the bearing shall be greased for life using grease type GPG-2LXEP complying with the requirements of Debswana specification DS 166014.

DS SPEC 373001



4.4 IDLERS

Idlers supplied in accordance with this specification shall be as follows:

4.4.1 Number of rolls: for impact and troughing idlers shall be 3 rolls for belts up to and including 1200 wide, and 5 rolls for belts over 1200 wide unless otherwise specified by the Engineer.

4.4.2 Type

• Troughing idlers : Offset

• Impact idlers : Offset

• Return idlers : Single roll flat return

Replaceable rubber disc

Fixed form 10° Vee return

4.4.3 Series: idlers shall be of the following series as specified in SANS 1313 and shall be specified by the Engineer (see Clause 2.8).

• Impact idlers : Series 30 and or 25

• 3 roll troughing idlers : Series 25 and or 20

• 5 roll troughing idlers : Series 25 and or 20

• Return idlers for belts up to and including 1 500mm wide

: Series 25 and or 30 for flat and Vee return. Series 25 and 30 for replaceable rubber disc.

• Return idlers for belts over 1 500mm wide

: Series 30

4.4.4 Drop height of flat return idlers: shall be 40mm or 90mm, as specified by the Engineer.

4.4.5 Mounting brackets: shall be manufactured from steel to SANS 1431 Grade 300WA. Construction and design shall be such that belt damage shall be minimal in the event of rolls becoming detached.

The bracket seat supporting the roll shall not be less than 8mm for 20 series, 10mm for series 25 idlers and not less than 12mm for series 30 idlers.

DS SPEC 373001



4.4.6 Rollers for Diving Head Chutes

Rollers for diving head chutes are generally specially designed for the particular application. The roller sizing is dependant on the belt width, speed, tension and roller curve radius. Standard flat idlers in accordance with this specification and SANS 1313 may only be used in special conditions and are system-specific. The design of the rollers in the diving head must be refered to the technical design office for final sizing. A typical solid roller for a 1 350mm wide belt at a belt speed of 2.6m/s and a belt tension of 153kN on a curve radius of 2.0m is shown in the sketch below:

4.4.7 Troughing angle: troughing angle shall be one of the following as specified by the Engineer:

• 20°

• 35°

• 45°

Provision shall be made for adjustable intermediate troughing angles for transition between flat and fully troughed sections of the conveyor in accordance with the conveyor belt manufacturers recommendations.

4.4.8 Direction of belt travel: shall be clearly marked on all troughing idlers.

4.4.9 Angle of forward tilt: outer inclined rolls shall be tilted forward in the direction of the belt travel to assist training where specified by the Engineer. The angle of tilt of outer inclined wing rolls shall be the minimum commensurate with the application and shall not exceed 3°for belt widths up to and including 1 050mm or 1.5° for belt widths above 1 050mm. The tilting of wing idlers is not applicable to reversible conveyors.

4.5 CORROSION PROTECTION - MOUNTING BRACKETS

Corrosion protection shall comply with the requirements of Debswana Specifications DS 164050.

The colour of the final coat shall be as specified by the Engineer (see Clause 2.9).

φ150

φ100

1350

1830

1960

R75

DS SPEC 373001



5 QUALITY ASSURANCE PROVISIONS

5.1 QUALITY MANAGEMENT REQUIREMENTS

Debswana QAP 101 shall apply.

5.2 DRAWINGS

Contractors shall submit certified general arrangement drawings with sufficient detail to prove compliance with the requirements of this specification. Drawings shall be approved in principle by the Engineer prior, to contract award.

5.3 DESIGN CALCULATIONS

Shall be supplied with tenders proving that idlers and rolls comply with the requirements of this specification. (See Appendix C)

5.4 SAMPLING FOR INSPECTION AND TEST

Shall comply with the requirements of SANS 1313.

5.5 GUARANTEE

The Contractor shall guarantee idlers against all defects attributable to faulty manufacture, workmanship and quality of materials for a period of one year after installation. Idlers that fail before one years normal service shall be replaced free of charge by the Contractor.

6 TEST AND INSPECTION METHODS


7 MARKING AND PACKING

7.1 MARKING


7.2 PACKING

Idlers and rolls shall be packed in such a manner as to prevent damage during transit.

DS SPEC 373001



APPENDIX A: RELATED DOCUMENTS

Debswana specification DS 164050

Debswana specification DS 166014

Debswana QAP 101

BS 970 PART I

BS 5512

ISO 15

SANS 657 PART III

SANS 723

SANS 1274

SANS 1313

SIS 05 5900

APPENDIX B: RECORD OF AMENDMENTS

Issue 0 : Based on De Beers Specification

DS SPEC 373001



APPENDIX C: RELATED CALCULATIONS

Calculations on the design of Debswana conveyor idler rolls.

Misalignment

The required static load S is given in Clause 4.3.2.

( )π

−=

EI4180A2GWAQ

(1)

Where Q = Misalignment in degrees

A = Distance from centre of bearing to center of nearest roll support (mm)

E = Modulus of Elasticity = 210 000 N/mm²

I = Moment of Inertia = 4dx64/π

d = Shaft diameter at the bearing (mm)

G = Gauge length (mm)

W = 2S x 9.81 (N)

From (1)

Q = ( ) 4d/A2GWA0014.0 − (2)

Design Life

Select bearings using bearing calculations as published by bearing manufacturers to allow for the following:

W (N) as previously calculated x 0.5

Q (degrees) as previously calculated

L 10 life rating = 75 000 hours

Rotational speed = 375r/min

Documents

Debswana Spec 373001