A.02 SOW 4th contract.docx

Statement Of Work Rehabilitation and Re-tubing Thrust Bearing Coolers at John Day Dam

1.0 General

This specification is intended to define materials and services required to rehabilitate 3 each, finned heat exchangers Thrust Bearing Coolers sets use to cool thrust-bearing oil in hydroelectric General Electric turbine generators. Fresh river water flows through the tubes which are immersed in a bath of ISO 68 DTE Heavy Medium turbine oil. Each cooler set is comprised of two semi-circular halves. Each cooler half is constructed of a frame supporting 24 finned tubes with a supply/ discharge manifold on one end and a return header on the other.

Prior to beginning work all material, detailed construction drawings and an Operation and Maintenance Manual will be submitted to the Government for approval. As built drawings will be provided with the coolers including heads and placed in the O&M manual when delivered with 3 paper copies and in digital format.

All tubing, cooling fins, and gaskets must be replaced due to wall thinning and leakage causes by wear and /or corrosion. Leakage in a cooler would result in shutdown of the generator, loss of carbon free electrical production and a major disassembly to access the tub. These units are critical parts and the highest quality is required in manufacture.

Unit is to be disassembled, cleaned and sealing surfaces resurfaced to flat for sealing. A side and B side will be marked to ensure the manifold side head is correct for targeting as they are not identical.

The unit is to be inspected after receiving it and any additional findings reported to the Contracting Officer as soon as possible.

The cooler sets will be retubed over the period of the contract.

2.0 Tubing

The replacement extruded tubing shall be made of 90/10 Cu Ni SB111 C70600 with a minimum wall thickness of 0.049” (existing) to a maximum of 0.065”. Tubing OD shall be 1.00 inch. The tubes are two different lengths and radii. There are 12 tubes of each length for each half, 24 tubes on each half; totaling 48 tubes per full thrust bearing oil cooler set.

Approximate lengths of the tubing are 17’ 1-3/8 inch inner and 17’ 9 5/8 outer. Approximate radii to tube centerline are 6’ 3” and outer 6’ 6”. The fins shall be finned 7 to 9 fins per inch. The fins shall be aluminum and shall be extruded. The fin outside diameter shall be 1.875 to 2.01”. Fin thickness shall be a minimum of 0.012 to a maximum of 0.016. Damage to the fins such as bending and separation from the tubing may occur when the tubes are inserted into the frame. Not more than 1% noticeable fin damage is allowed in the finished cooler. Manufacturer’s specification of the proposed finned tubing and a sample of the extruded tubing shall be submitted as part of the bid.

Tube rolling shall conform to TEMA standards and ASME standards for Heat Exchangers including wall thinning after rolling.

3.0 Manifolds

A new contractor supplied gasket shall be installed on each head. The gasket shall be a semi-rigid non –asbestos type formulated for both oil and water service. The government will not provide gaskets.

The gasket will be installed using permatex #2 sealant. Gasket material shall be trimmed flush with the periphery of the head and tube sheet if needed. Heads will be machined flat if required to allow sealing.

4.0 Hardware

All damaged hardware shall be replaced with like materials. All fasteners will be replaced with bolts or cap screws that meet SAE J429 Grade 8, with matching washers. The approved lock washers used shall be wedge self-locking type , not classical split washers. Replacement hardware shall be plated to resist corrosion.

Proper anti seize will be applied on threads to prevent galling. A torque table will be supplied and indicated on as built prints designating torque and lubrication for future assembly. The torque pattern for the heads will be listed on the drawings and provided in the manual.

A new nameplate with manufacture’s data and A side or B side will be included.

5.0 Cleanliness and Testing

The coolers will be delivered to the government in a clean condition so that no cleaning is needed prior to installation. No metallic particles or other foreign mater shall be visible on the coolers.

Each complete cooler shall receive a hydrostatic pressure test at 75 PSIG In accordance with Pressure Vessel Standards. The pressure must hold for a minimum of 1.5 hours. Written documentation of the test shall be provided. At the discretion of the Government, a Government representative may inspect both the on-going work or the pressure testing of the coolers.

6.0 Packaging and Shipping

The contractor shall be responsible for providing transportation to and from The John Day Dam Powerhouse east of Rufus, OR. The cooler halves will be picked up in Government-provided shipping crates. Each shipping crate measures approximately 14 feet long by 5.5 feet wide and 4.5 feet high. The weight is approximately 2,200 pounds for one cooler half, two in total for 4,400 pounds. The crates may not be stacked. Contractor shall insure adequate protection from damage in transit and the contractor shall be responsible for and make good any or all damage to either coolers that may occur prior to acceptance by the government at the specified delivery point at John Day Powerhouse.

All shipments are FOB Destination. Contractor will pay for all shipping related costs in both directions. Government crane service will load and unload the crates.

John Day is on a 4 day work week and the Warehouse hours are Only Monday thru Thursday 0700 -1600 Pacific time. Any other transportation arrangements shall be made well in advance prior to transportation departure and with written approval from the Contracting Officer’s Representative (COR).

7.0 Head Replacement

Replace by fabrication using all new materials the Eight heat exchanger heads, that includes the Four End Heads and the Four Manifold Heads with piping and flanges for both sets of coolers.

New heads will be modeled on the existing heads with an impingement plate as needed and will meet TEMA standards. The heads will be paint coated to prevent corrosion.

The current steel heads are @35 inches long by @ 8 inches wide with 52 closely spaced bolt holes with 4 ½ NPT pipe plugs, 2 at the top and 2 at the bottom. Two of the four heads, the supply/discharge manifold head, contain inlet/outlet 2 inch steel piping with 150 pound flanges. New manifold heads must have the piping and flanges exactly targeted with existing cooler to ensure fit when reinstalled.

It is important that All the old heads will be retained and returned to the project in the repaired cooler shipping container when the coolers are shipped back and be listed on the shipping papers.

A separate basic dimensional outline drawing of the new heads will be provided showing material and coating system used. A drawing of any gasket delivered will be provided so local gaskets can be made in the future.

8.0 Quantities for Each Cooler Set of Two Cooler halves.

1. New End Heads- Quantity 4

2. New Manifold with piping Heads- Quantity 4

3. Extruded tubing for retubing

4. One full set spare set of 4 gaskets for each cooler set.

5. Fasteners and hardware.

6. The Manual and As Built Drawings of cooler sets and new heads need to be provided with delivery of each unit. Manual will include Torque specs for fasteners , including anti seize lubrication used, and a tightening sequence. Three copies in paper and one in approved electronic format are required.

7. Each cooler set will be labeled A side or B side on the new nameplate.