Shaftless Screw Conveyor

PART 1 GENERAL

1.01       SCOPE OF WORK

A. Furnish all labor, materials, equipment, and incidentals required to install and test, complete and ready for operation, one shaftless screw conveyor as shown on the Drawings and as specified herein.

B. The units shall be furnished by the centrifuge manufacturer and installed with all necessary accessory equipment and auxiliaries, whether specifically mentioned in these Specifications or not, as required for an installation incorporating the highest standards for the type of service including field testing and instructing the regular operating personnel in the care, operation and maintenance of all equipment.

C. Electric motors shall be furnished as part of the scope of work of this section; and shall be in accordance with this Section.

1.02       RELATED WORK

A.   Concrete work is included in Division 3.

B.    Painting, except as specified herein, is included in Division 9.

C.    Electrical, except as specified herein, is included in Division 16.

D.   Instrumentation, except as specified herein, is included in Division 13.

E.    Mechanical piping and appurtenances, valves, pipe hangers and supports are included in
Division 15.

1.03      SUBMITTALS

A. Submit, In accordance with this Section, six copies of all materials required to establish compliance with these Specifications and shall include the following:

1. Certified shop and erection drawings showing details, sizes, grades, and materials of construction; dimensions; and any anchor bolt locations.

2.    Descriptive literature, bulletins, and catalogs of the equipment.

3. The total weight of the equipment including the weight of the single largest item or component, both when empty and when loaded with the maximum specified load of wet debris.

4.    Complete bill of materials for all equipment components.

5. List of the manufacturer's recommended spare parts. Include gaskets, packing, etc. on the list.

6.    Documentation of the AGMA rating of the drive assembly.

7.    Details of the torque overload device.

8.    Complete description of surface preparation and shop prime painting.

9.    Complete data on motor in accordance with this Section.

10.  Manufacturer's Warranty as specified in this Section.

11.  Factory test results as specified in PART 3.

B. In the event that it is impossible to conform with certain details of the Specifications, describe completely all non-conforming aspects.

C.    Operation and Maintenance Data

1. Furnish sets of operating and maintenance instructions as specified in this Section. Prepare them specifically for this installation, and include all required cuts, drawings, equipment lists, spare parts, descriptions, and other information as required to instruct operating and maintenance personnel unfamiliar with this equipment. Include copies of all approved shop drawings in the Operation and Maintenance Manuals.

D.   Submit the manufacturers' certification of proper installation and operation as required in PART
3.

E.    Additional Submittal Requirements

1.    Shop drawings of all fabricated items, structural supports, and associated items.

2. The conveyor support systems shall be designed by the manufacturer for all applicable loads (dead, live, dynamic, etc.), for normal and seismic conditions. Design loadings shall be transmitted to the concrete foundation. Design calculations for all of the items covered by these Shop Drawings shall be submitted to the Engineer and signed/sealed by a registered professional engineer in the State of Wyoming and shall show design stresses in all structural members and connections. Fabrication of the conveyor systems and supports shall not commence until shop drawings have been approved.

3.    Size, length and spacing of anchor bolts or attachments to the concrete foundations.

4. Detail installation and layout drawings, specifications and catalog cut sheets of all items of equipment showing all dimensions, parts, construction details, and materials.

5.    Wiring Diagrams.

1.04       REFERENCE STANDARDS

A.   American National Standards Institute (ANSI)

B.    American Institute of Steel Construction (AISC)

C.    American Society of Testing and Materials (ASTM)

D.   American Gear Manufacturers Association (AGMA)

E.    Conveyor Equipment Manufacturers Association (CEMA)

F.    National Electrical Manufacturers Association (NEMA)

G.   Occupational Safety and Health Administration (OSHA)

H.   American Welding Society (AWS D.1.1-90)

I.     American Bearing Manufacturer's Association (ABMA)

J.     National Electric Code (NEC)

K.   Society for Protective Coatings (SSPC)

1.05      QUALITY ASSURANCE

A. The equipment covered by these Specifications shall be the product of a single reputable and qualified manufacturer who is of proven ability.

B. These Specifications call attention to certain features, but do not purport to cover all details entering into the construction of the equipment.

C. Should equipment which differs from these Specifications be offered and determined by the Engineer to be the equal of that specified, such equipment shall be acceptable only on the basis that any revision in the design and construction of the structure, piping, appurtenant equipment, electrical work, or any other portion of the work required to accommodate such a substitution be made at no additional cost to the Owner and be as approved by the Engineer.

D. The equipment shall be as manufactured by JDV Equipment; Spirac; Jim Myers & Sons, or equal. These named manufacturers' standard products may or may not conform to these Specifications, and in case of conflict between these Specifications and a manufacturer's standard products, these Specifications shall have precedence.

E. The manufacturer shall furnish an engineer experienced in the erection, alignment, and operation of the equipment furnished under this Section for a minimum of one trip for a minimum total time at the site of not less than one day, which includes certifying its readiness for operation. Each day shall include a full eight-hour working day on the project site; travel time shall be additional to these requirements.

F. A factory representative who has complete knowledge of the proper operation and maintenance of the equipment furnished shall be provided for one day as defined above, and in addition to the days required above, to instruct representatives of the Owner and Engineer on proper operation and maintenance of the equipment. An additional trip is not necessarily required, if the training can be satisfactorily scheduled as an extension of the installation and inspection trips, as provided hereunder and provided that the final operational test is successful, and provided that the Operation & Maintenance Manuals instructions have been furnished and approved.

1.06       DESCRIPTION OF SYSTEM

A. Screw Conveyor shall be design to convey the dewatered sludge from the centrifuge to the truck load-out hopper without sustaining structural or mechanical damage.

B. All items furnished shall be amply designed and constructed for the maximum stresses occurring during fabrication, installation and both continuous and intermittent operation.

1.07      MAINTENANCE

A.   Furnish all special tools required for normal operation and maintenance of the equipment.

B.    Provide spare parts for each screw conveyor.
1.    2 bearing assemblies.

1.08        MANUFACTURER’S WARRANTY

A. The DESIGN/BUILDER shall obtain from the manufacturer its warranty that the screw conveyor will be free from defects in design, materials, and workmanship for a period of one year following Substantial Completion. Said warranty, containing no exclusions or limitations, shall be in a form acceptable to and for the benefit of the Owner, and shall be submitted by the DESIGN/BUILDER as a condition of Final Payment.

PART 2 PRODUCTS

2.01 MATERIALS AND EQUIPMENT
A. General
1. The shaftless screw conveyor system specified herein shall be furnished by one manufacturer with a minimum of five years experience in the manufacture of shaftless screw waste treatment conveying systems installed in municipal wastewater treatment facilities.  The shaftless screw conveyors shall be supplied directly by a manufacturer with not less than fifty separate operating installations of shaftless conveyors of its own manufacture, that are similar size and capacity as the systems specified herein.

2. All parts furnished shall be amply designed and constructed for the maximum stresses occurring during fabrication, erection and continuous operation. All materials for the conveyors and cleaning systems shall be new and shall be of the very best quality, entirely suitable for the service to which the units are to be subjected and shall conform to all applicable Sections of these Specifications.

3.    All parts of duplicate equipment shall be interchangeable without modification. Manufacturer's design shall accommodate all the requirements of these specifications.

4. All supports for conveyors shall be provided for the conveyor support framing. The DESIGN/BUILDER shall be responsible for coordinating the placement all supports necessary to tie the equipment together and shall have the undivided responsibility for the system's structural integrity.

5. Exposed welds shall be ground smooth to form a neat uniform fillet without weakening the base metal.

6. Molded shaped members shall be formed with clean, sharp rises without dents, scratches, cracks or other defects.

7. Shop Welding: Screw conveyor manufacturer's shop welding procedures, welders and welding operators shall be qualified and certified in accordance with the requirement of AWS D1.1 "Welding In Building Construction". Shop drawings shall clearly show complete information regarding location, type, size and length of all welds in accordance with AWS A2.0 "Standard Welding Symbols". Special conditions shall be fully explained by notes and details.

B. All structural supports shall be provided for the conveyors' support. The manufacturer shall be responsible for coordinating the placement of all supports necessary to tie the equipment together and shall have the undivided responsibility for the system's structural integrity. Detailed drawings and calculations, signed by a professional engineer licensed in the State of Wyoming, shall be submitted to the Engineer for review and comment prior to fabrication.

C. Except where specifically allowed by the Engineer, all hardware including washers, clips, clamps and fasteners of any type shall be constructed of Type 304L stainless steel. All anchor bolts shall be Type 316 stainless steel and have a minimum of 3/8-in diameter.

D.   Design Requirements

1. The screw conveyor shall be a shaftless design that is capable of conveying 20-30% solids dewatered sludge, weighing 60-65 PFC, at a rate of approximately 200 cubic feet per hour. Under no circumstances shall the dewatered sludge be discharged from the conveyors except through designated outlets. The configuration of the unit shall be push type.
Adequate seals shall be provided on the drive end to prevent material from entering the gear box.

2. The conveyor shall be designed and manufactured to handle intermittent loading of dewatered sludge from the centrifuge to the truck load-out hopper 24 hours per day, 7 days per week. The torque capacity of the drive unit shall be sufficient to start the conveyor with
100 percent trough loading.

3. Operating Parameters including length, incline, pitch, flight diameter, inlets, outlets, gates, and drive requirements shall be as shown on the schedule below.


Screw Conveyor Location: Dewatering Building  
Classification: Unclassified  

Screw Length (ft): 36 (to be verified based on selected centrifuge)  

Pitch (degrees): 5 (to be verified based on selected centrifuge)  

Inlets: Connected to Centrifuge Discharge (Coordinate sizing with centrifuge manufacturer)  

Outlets: Discharge outlet (size based on shaft diameter), 4‐inch dia drain  

Gates: None  

Drive Requirements: Per Manufacturer calculations

E.    Materials

1. Trough, Chutes: 304L Stainless Steel  

2. Covers:        14 Ga Min 304L Stainless Steel  

3. Drive & End Plates:  1/2-in Min 304L Stainless Steel drive, 3/8-in non-drive  

4. Spiral Flighting: Minimum 254 mm diameter, 80,000 lb. yield, with spiral insert, Micro-Alloy min. 250 Brinell Hardness  

5. Wear Liner: Plastimeric, (UHMW), 1/2-in thick min.  

6. Hardware:     Type 304L Stainless Steel  

7. Cover Fasteners:     Type 304L Stainless Steel bolts

8.    Drive Shaft:      AISI 1045 steel

F.    Spiral Flighting

1. Spiral flighting for the shaftless screw conveyors shall be designed to convey material without a center shaft. The minimum overall spiral weight and surface pressure shall be as specified herein. The conveyor will include an inner flight to increase axial strength and capacity of the conveyor. The minimum spiral weight shall be specified herein.

2. Spiral flights shall be cold-formed high strength chrome alloy steel with a minimum hardness of 250 Brinell and the bar thickness shall not vary by more than 20 percent from the outer edge to the inner edge. The spiral flights shall be designed with the stability to prevent distortion and jumping in the trough. The torsional rating of the auger flighting such that, at 150 percent of the motor nameplate horsepower, the drive unit cannot produce more torque max. than the torsional rating of the flighting, and that the "spring effect" of the spiral shall not exceed plus 0.7 mm per 100 mm of length at maximum load conditions.

3. The spiral flighting shall be formed in sections from one continuous flat bar and shall be concentric to within 2mm plus/minus. Sectional flighting formed from plate shall not be permitted.

4. Spiral flighting shall have full penetration welds at all splice connections. The flights shall be aligned to assure true alignment when assembled in the field and shall be made in accordance with the supplier's requirements. The spiral flights shall be coupled to the end shaft by a flanged, bolted connection.

5. A gland packing ring consisting of two Teflon coated packing rings shall seal the drive shaft at its penetration through the end plate, along with a greased labyrinth sealing system.

6. The connection of the spiral to the drive system shall be through a flanged connection plate that is welded to the spiral forming a smooth and continuous transformation from the flange plate to the spiral. The drive shaft shall have a mating flange and shall be bolted to the spiral connection plate.  Additionally, a grease lubricated labyrinth seal shall be shaft mounted internally in the conveyor between the back plate and spiral coupling connection.

G.   Trough and Liner

1. Troughs shall be similar to the dimensional standards of CEMA 300 and enclosure classification IIE. Each conveyor trough shall be U-shaped, fabricated from a minimum 1/8-in Type 304L stainless steel plate.  Stiffeners shall be placed across the top of the trough and fastened to both sides of the trough to maintain trough shape and act as a face seal for the covers; apply a continuous gasket, totaling one half inch width, to the entire top face of the trough top flange and stiffeners. The gasket shall be Buna-N rubber, 1/8-in thick with a Durometer hardness of 40.

2. Each trough shall be equipped with filling and/or discharge openings as required by the contract drawings. The filling opening shall be flanged and suitable for interconnection to the centrifuge. Any interconnecting devices such as chutes and hoppers shall be fabricated from the same grade of material as the troughs and to a gauge to suit the applications requirements.

3. A discharge port shall be provided at the discharge end of the conveyor for sludge discharge to load out.

4. The lowest point of the conveyor trough at the centrifuge end shall include a 4" minimum diameter drain connection. The outlet shall be piped to a drain as shown on the drawings, along with adequate cleaning facilities.

5. The portion of each trough that is not covered by the filling chute shall be covered by a stainless steel cover with gasketing per 2.01.E. Covers shall be held in place with stainless steel screw clamps or bolts on 24” maximum centers. The covers shall be manufactured in maximum five foot length section to allow for access to the conveyors. The covers shall have a 1 inch turndown edge on the two long sides. To prevent unsafe access to the conveyors, quick opening covers will not be allowed.

6. The trough shall include a replaceable wear liner fabricated of ultra high molecular weight polyethylene (UHMWP) per 2.01.E. The liner shall be impregnated with a lubricant material to reduce liner wear and extend operational life. The wear liner shall be furnished in maximum four foot sections to provide ease of replacement. The liner shall be held in place with permanently welded clips positioned at each liner end, mid point and spanning liner joint; no fasteners which penetrate the trough will be allowed. The liner shall be provided with a visual indication of excess wear.

7. Trough ends thickness shall be per 2.01.E and include top flange and support foot. The drive-end trough end shall include provisions for drive support and shaft seal packing replacement and adjusting.

H.   Conveyor Supports

1. Each conveyor shall be furnished complete with supports suitable for mounting as shown on the contract drawings and as required by the supplier's design. The supports shall be shop fabricated. Supports shall be fabricated from Stainless Steel grade 304L. Supports shall be assembled and test fitted to the conveyor prior to its delivery to the jobsite and then disassembled ready for shipment. Supports and conveyor segments shall be match marked and shipped to the jobsite for assembly by the general DESIGN/BUILDER or others. At a minimum, each conveyor shall be provided with supports at the inlet and discharge end, with intermediate supports as required.

2. All shop welding shall conform to the latest standards of the American Welding Society (AWS). The supports shall be designed to avoid interference with other equipment or equipment supports.

3. All structural supporting members shall be designed such that the ratio of the unbraced length to least radius of gyration (slenderness ratio) shall not exceed 120 for any compression member and shall not exceed 240 for any tension member (of angles about Z- Z axis). In addition, all structural members and connections shall be designed so that the unit stresses will not exceed the American Institute of Steel Construction allowable stresses by more than 1/3 when subject to loading of twice the maximum design operating torque of the spiral conveyor drive motors.

I.     Drive Units

1.    Motors shall be supplied as noted herein.

2. Each spiral conveyor shall be driven by a constant-speed integral gear reducer/motor drive unit mounted to an adapter flange mounted to the end plate of the conveyor (centrifuge end per the Drawings). The adapter flange shall allow the leakage of any material from the conveyor trough to atmosphere rather than into the gear reducer/ motor drive unit. Direct coupling of the gear reducer/motor drive unit to the end flange of the conveyor will not be acceptable.

3. The drive unit shall be rigidly supported so there is no visible "wobble" movement under any operating condition. In the event of a prolonged power failure or emergency system shutdown the drive system shall be designed, at a minimum, to start the conveyor from a dead stop with the trough filled throughout its entire cross sectional area and length with partially dried and hardened dewatered material.

4. Each motor shall be 460 Volt, 3 Phase, 60 Hz, TEFC, severe duty motor with 1.15 SF and class F insulation. Motor and appurtenances shall have Design B speed/torque characteristics suitable to start with the conveyor fully loaded without using the service factor..

5. The motor shall be provided with internal thermal switches to monitor the temperature of each phase winding. These thermal switches shall be supplemental to external motor overload protection and shall be connected to the control circuit.

6. Gear Reducers. All gears shall be AGMA Class II, single or double reduction, helical gear units with high capacity roller bearings. Bearings shall be designed for the thrust loads from the fully loaded startup condition and shall have a ABMA B10 life of 30,000 hours.
The reducer will be the standard air cooled unit with no auxiliary cooling. The gear reducer shall be sized with a torque service factor of 2.0 times the absorbed power or 1.5 times the motor nameplate, at the driven shaft speed, whichever is greater.

7. Motion Failure Alarm Unit. Each conveyor drive unit shall be equipped with a motion failure alarm unit with stainless steel mounting hardware. The location and mounting
details shall be as recommended by the conveyor manufacturer. Motion sensors shall be the non-contacting type using a probe with a pre-amplifier and main electronic assembly. The main electronic unit shall operate on 120 Volt, single phase, 60 Hz power supply, and shall be housed in a NEMA 4X enclosure. A 0 to 60 second time delay shall be provided for startup of the conveyor.

J.     Cable Operated Safety Switch System (Emergency Pull Cord)

1. An emergency pull cord and switch shall be located on one side of each conveyor as indicated on the Drawings.

a. Switches shall be activated by pulling on the tag lines, which shall run the full length of the conveyor.

b. Switches shall have manual reset flag arm and a positive safety lock to prevent accidental reset of the switch.

c. Switches shall be housed in a Feraloy Iron Alloy Enclosure with stainless steel plunger and corro-free epoxy powder coat finish with gaskets.

d.    Switch shall be rated for 120 VAC electrical service.

e.    Switches shall be Crouse-Hinds AFUX Series or equal.

2.    The actuating force on cable shall be field-adjustable.

3. The pull cord shall be 3/32-in 7 x 7 galvanized aircraft cable with orange colored protective vinyl or mylar coating (3/16-in OD).

a. Pull cord support eyebolts shall be Type 316 stainless steel and shall be provided at a maximum spacing of ten-foot centers.

b. Pull cord shall be arranged so that it extends out from the frame providing easy operation.

K.   Safety
1.    All necessary safety equipment and guards to meet OSHA requirements shall be provided.

L.    Instrumentation and Controls
1.    Provide H-O-A local switch for normal operations.
2.    Start / Stop signal shall originate from the Centrifuge Control Panel
3. Alarm conditions shall be transmitted to the Centrifuge Control Panel for integration into the SCADA System.
4.    Fail Conditions shall be transmitted to the Centrifuge Control Panel for integration into the SCADA System.

2.02      ANCHOR BOLTS

A. The manufacturer shall design the anchor system and provide and all anchor bolts required for the installation of the equipment shall be furnished by the equipment manufacturer. Anchor bolts shall be Type 316 stainless steel.

2.03      SHOP PAINTING

A.   All exposed steel surfaces shall be prepared and shop primed in accordance with Section 09901.

PART 3 EXECUTION
3.01       INSTALLATION

A. Installation and initial lubrication shall be in strict accordance with the manufacturer's instructions and recommendations in the locations shown on the Drawings. Installation shall include furnishing the required oil and grease for initial operation. Anchor bolts shall be set in the concrete in accordance with the manufacturer's recommendations and setting drawings.

B. The DESIGN/BUILDER shall be responsible for the coordination of this equipment with the requirements of the belt conveyor to obtain a complete, integrated, and satisfactory operating installation.

3.02       FIELD PAINTING

A.   Field painting is included in Section XXXX.

3.03      FIELD TESTING

A. The manufacturer's engineer shall inspect the final installation and supervise a test run of the equipment.

B. Working under the direction of the manufacturer's engineer, and in the presence of the Engineer, the DESIGN/BUILDER shall perform dry field tests on the screw conveyor as follows:

1. First, the screw conveyor shall have a dry test run to demonstrate the correct alignment, smooth operation, proper and equal spacing of screen bars, freedom from vibration, excessive noise and overheating of the parts and bearings.

2. Secondly, an overload torque test shall be conducted to test the torque overload device to operate and stop the screw conveyor at a loading condition equal to 150 percent of the actual working load of the drive or as required to protect the drive unit, whichever is less. The necessary adjustments and settings to the overload device shall be made at this time to ensure that the screw conveyor will stop, switch off the drive motor, and sound an alarm when a predetermined overload condition occurs in the screw.

C. Once solids are available, the screw conveyor shall be operated for a period of not less than 8 hours. The units shall operate without binding, clogging, excessive noise or vibration, overheating and to demonstrate proper solids collection and discharge.

D. In the event of improper installation or improper operation, all defects shall be corrected, at no additional cost to the Owner, until the equipment operates to the satisfaction of the Engineer.

E. Submit a certificate from the manufacturer stating that the installation is in complete accordance with the manufacturer's requirements, that the equipment is ready for operation, and that the operating personnel have been suitably instructed in the operation, lubrication, and care of the equipment.