Statement of Work Refurb 4 sets Heat Exchangers.pdf

Portland District

THE DALLES DAM

THE DALLES, OREGON

THRUST BEARING OIL COOLER

REFURBISHMENT

Units 1-14, 4 Sets

July 2022

STATEMENT OF WORK

PART 1 GENERAL

1.1 GENERAL INFORMATION

This specification is intended to define materials and services required to rehabilitate heat exchangers that are used to cool oil in a hydroelectric turbine generator thrust bearing. River water runs through the tubes, which are immersed in a bath of oil. Each cooler is comprised of two semi-circular halves that are mirror images of each other. Each half is constructed of a frame supporting 48 finned tubes with a supply/discharge manifold on one end and a return header on the other end. Tubing connections are accomplished by rolling each tube end into a brass tube sheet.

1.2 REFERENCES

The publications listed below form a part of this specification to the extent referenced. The publications are referenced in the text by basic designation only.

ASTM A193 Medium Strength Steel Studs

ASTM A325 Structural Fasteners

ASTM B 36 Brass Plate, Sheet, Strip, Rolled Bar

ASTM B 111 Copper and Copper-Alloy Seamless Condenser Tubes.

ASTM B 171 Brass Plate for Condenser Tube Sheets

ASTM F 436 Medium Strength Washers

SAE J 429 Steel Fasteners

UNS C70600 90-10 Copper-Nickel Plate

UNS C46400 Naval Brass

1.3 TECHNICAL CONTACT

Garrett Hall

US Army Corps of Engineers

The Dalles Dam

PO Box 564

The Dalles, OR 97058

(541) 841-4834

Garrett.A.Hall@usace.army.mil

1.4 DELIVERABLES

Four refurbished heat exchanger sets and documentation of pressure tests.

PART 2 PRODUCTS

2.1 NEW FINNED TUBING

2.1.1 Tubes shall be straight without burrs, scratches, or kinks, on the inner or outer surfaces.

The attachment of the fins shall not damage the surface of the tube or in any manner impair the mechanical integrity of the tube wall. All tubes shall have a clean surface to assure a good mechanical bond when fins are attached. Tubing for the rehabilitated coolers shall be new. No more than 1% fin damage is allowed in the finished, delivered cooler. Note there are six gaps along each tube where there are no fins to allow the intermediate supports to clamp directly to the tube.

2.1.2 Manufacturer’s technical literature shall be submitted to the technical contact and approved before the tubing is ordered.

2.1.3 The replacement tubing shall be made of ASTM B111, UNS No. C70600, 90/10 Copper

Nickel with a wall thickness of 0.065 inches. Nominal tubing OD shall be 3/4 inches. The tubing shall be finned. The fins shall be copper and shall be edge tensioned, spaced at 7 fins per inch.

The fin outside diameter shall be 1.5 inches. Fin thickness shall be a minimum of 0.012 inches to a maximum of 0.016 inches. The tubes are 3 different lengths of 16 tubes each. Approximate lengths are; Inner 184”, mid 190” and outer 202”. Approximate radii are 68”, 70, and 74”.

2.2 TUBE SHEET

It is anticipated the original tube sheets will be reused. If significant deterioration is observed that would make it difficult to reuse the tube sheets or would affect the service life, the contractor shall notify the POC before proceeding and specify the additional cost. The contractor must receive approval from the contracting officer before replacing tube sheets.

2.3 TUBE ROLLING

Tube expansion shall be accomplished by rolling using the latest industrial methods and standards. Tubes shall be rolled so as not to impair the strength nor reduce the wall thickness outside the tube sheet. Care shall be taken to not over roll the tubes at the tube to tube sheet interface.

2.4 HEADERS & COVER PLATE

It is anticipated the original return headers and cover plates will be reused. If significant deterioration is observed that would make it difficult to reuse these components or would affect the service life, the contractor shall notify the POC before proceeding and specify the additional cost. The contractor must receive approval from the contracting officer before replacing these components with new.

There is a length of 5/8 copper tubing installed in the inlet/outlet cover. Remove this tubing and install a brass pipe plug.

2.5 GASKETS

New gaskets shall be installed. The gasket shall be a semi-rigid non-asbestos type that is formulated for both oil and water service. The gasket shall be installed using Silicon RTV sealant. Gasket materials shall be trimmed flush with the periphery of the head and tube sheet.

2.6 TEST COUPONS

Include four 8” long test coupons in each half of the cooler, of identical build to the rest of the finned tubing. Install the coupons in the outer most row of tubes, with one end of each coupon 6” from the intermediate support. Coupons will be installed using vibration resistant threaded compression fittings at both ends. Provide 8 additional loose coupons to replace the ones removed for inspection.

2.6 FASTENERS

The vendor shall replace all bolts, studs, dowel pins, nuts and washers. Bolts shall meet ASTM

A325 Type 1 or SAE Grade 5. Studs and dowel pins shall meet ASTM A193 Grade B7, and washers shall meet ASTM F436 Type 1. Nuts shall meet SAE Grade 5. An anti-seize compound shall be used on all threaded connections.

2.7 COATINGS

Any places on the steel frame that show corrosion shall be re-coated with clear Glyptal 1202 or an equivalent product made specifically for metal parts immersed in oil. Surface preparation and coating application shall be per the manufacturer’s recommendations.

PART 3 EXECUTION

3.1 GENERAL

Material shall be straight before being laid off or worked. If straightening is necessary, it shall be done by methods that will not impair or mar the metal. Material with sharp kinks or bends shall be rejected. Material with welds will not be accepted except where welding is definitely specified, indicated on the drawings, or otherwise approved. Where heating is required, precautions shall be taken to avoid overheating the metal, and it shall be allowed to cool in a manner that will not deteriorate the original properties of the metal. Shearing shall be accurately done and all portions of the work shall be neatly finished. Corners shall be square and true.

Finished members shall be free from twists, bends, and open joints. All bolts, nuts, and screws shall be tight.

3.2 DIMENSIONAL TOLERANCES

An allowable variation of 1/32 inch is permissible in the overall length of individual component members with both ends milled; individual component members without milled ends shall not deviate from the dimensions shown on the drawing by more than 1/16 inch.

3.3 FINAL DIMENSIONS

Each finished cooler shall fit into the space allocated for the original air cooler and attach to the generator without modification to the support points. The pipe flanges on the air cooler shall match the original generator piping without modification to either.

3.4 SHOP INSPECTION

The Contracting Officer’s Representative shall have access to the contractor’s facilities for unrestricted inspection. The acceptance of any material or equipment shall in no way relieve the contractor of his responsibility for meeting all of the requirements of the specification, and it shall not prevent subsequent rejection if such material of equipment is later found to be defective.

3.5 TESTING

The complete cooler shall be hydrostatically tested at 75 psi for a period of not less than one hour. Leaks found during testing shall be repaired by a government accepted method and the cooler retested until pressure is maintained. Proposed test method shall be submitted to the technical contact for approval. Documentation of the test shall accompany the cooler when it is returned.

3.6 CLEANLINESS

The coolers shall be returned in clean condition so that no cleaning is necessary prior to reinstallation. No foreign matter shall be visible on the coolers. Temporary covers shall be installed on inlets and outlets.

3.7 ADDITIONAL WORK

Work beyond that described in this specification, such as welding and machining, may be required for some coolers. Payment for additional work shall be negotiated on a case-by-case basis and shall be done by modification to the contract.

3.8 PACKAGING AND SHIPPING

3.8.1 The coolers will be removed from service and prepared for shipment by the Government.

The Government will provide reusable shipping crates and will load and unload the truck at The

Dalles Dam. The contractor shall be responsible for providing transportation to and from The

Dalles Dam Powerhouse. Crate dimensions are 14’ x 5.5’ x 4.5’ high. Total weight of each crated half is 4500 lbs.

3.8.2 The contractor shall prepare all coolers for shipment to the government in such a manner as to ensure adequate protection from damage in transit, and shall be responsible for and make good any or all damage that may occur prior to acceptance by the government at the specified delivery point.

3.8.3 The contractor shall be responsible for repairing damage done to the Government supplied shipping crates during shipment.

3.9 DELIVERY

The vendor shall be responsible for coordinating all transportation. Ship the coolers to The

Dalles Dam, Interstate 84, exit 88. Shipping charges shall be included in the bid item price.

Delivery shall occur between 0700 and 1500, Monday – Thursday excluding federal holidays.

3.10 SCHEDULE

The government plans to refurbish four sets of coolers with this contract, over the next 2 years.

The government will provide notification prior to the availability of the next cooler set, based on maintenance progression. Each completed cooler set shall be delivered back to the dam, no later than 6 weeks after it is made available to the contractor. Quantities may change depending on various maintenance factors.

PART 4 GOVERNMENT FURNISHED PROPERTY

1. Thrust bearing oil cooler(s) valued at $20,000 each. [The replacement value is more like

$80,000-$100,000, why is this so low?]

2. Reusable shipping crate(s) valued at $3000 each.

PHOTOS