CENTERPOINT ENERGY Materials Used in Sea Spray Environments

CENTERPOINT ENERGY Materials Used in Sea Spray

Environments

Presented by William R. GrimesField Inspections and Pictures by Glenn

Smith & Roderick Jefferson

CenterPoint Energy’s H.O.C./Brazosport Service Area, along the Gulf Coast,

Surfside, Texas

18 miles long and the majority of circuit within 350 feet of the Gulf of Mexico, and steady coastal winds. Typically there are no structures to block wind.

GALVESTON ISLAND: 29 Miles long effected by sea spray drops off as you move inland

3 Failure Modes and General Solutions1) Flashover during electrical storms due to lightning.

• Maintain high CFO target = 300 CFO, • Arrestors

2) Flashovers from leakage currents: Salt collects on equipment – light rains or high humidity create saline solution – leakage currents – flashovers occur as moisture evaporates• Longer leakage distances, • Hydrophobic surface (surface that expels water) verses hydrophilic surface (surface that attracts water), moisture breads VS spreading or sheen • Leakage resistance surfaces (polymer insulators and covering),• “hidden, unexposed” skirts (fog bowl insulators),

3) Atmospheric & dissimilar metal corrosion of metal components Loss of hardware strength – damage to equipment

• Corrosion resistant metals: Stainless steel, copper, bronze, aluminum, • Sacrificial coatings: zinc galvanized, zinc silicate• Paints & Coatings- Teflon, Wax Tape

Before 1986:

• Fog Bowl Pin Insulators (110 CFO) on wood crossarms

• Hot dipped Galvanized nuts, bolt, steel brackets (both fabricated steel and ductile iron cast),

• Stainless housing, banding and hardware for tanked equipment

WOOD X-ARM, STEEL PINS, and PORCELAIN FOG BOWL PIN INSULATORS

WOOD BRACE ENDS & HARDWARE DISINTEGRATED, ESPECIALLY BOLTS

CORRODING GUY WIRE & GUY GRIPS

Stainless Steel Transformer

Aluminum Fabricated

Bracket

Circa 1986:

• Post Insulators 210 kv BIL, 29” leakeage Distance on fabricated steel brackets

• Brackets bonded to system ground• Hot dipped Galvanized nuts, bolts, steel

brackets (both fabricated and ductile iron cast),

Hand Tied #2aaac soft

GALVESTON: * 35 kV DOUBLE CIRCUIT

CONSTRUCTION.* FABRICATED BRACKETS WITH

PORCELAIN LINE POST INSULATORS 29” LEAKAGE DISTANCE.

Circa 1999:

• Fog Bowl Pin Insulators (110 CFO) on polymer covered fiberglass brackets bonded to system ground.

• Aluminum fabricated or casting preferred over of hot dipped galvanized ductile iron casting or fabricated steel brackets,

• Stainless steel bolts (with bronze nuts), washers, spring washers.

• Stainless Steel guy wires and grips.

Fog Bowl Pin Insulators (110 CFO) on polymer covered fiberglass insulated brackets bonded to system ground.

Aluminum casting

Stainless Steel Spring Washer

Fabricated Steel

Brackets Galvanized ductile iron

Guy wire and grip study (2000 -2004)

• Status quo: “B” zinc thickness grade on guy wire and grips– ‘C” grade is just a heavier coating of the

same material.–Mischmetal is 95% zinc coating with 5%

aluminum. The manufacturer claims this coating will outlast “C” grade two-to-one.

–Stainless Steel- Much more expensive but out performed the other two products.

Guy wire and grip study (2000 -2004)

Guy wire and grip study (2000 -2004)

Guy wire and grip study (2000 -2004)

RECENT (2005-2009): • Aluminized (aluminum extruded over steel core)

– steel guy wire and grips,– grips #2aaac, 4/0aaac and 600aac .

• Zinc-silicate coatings on nut, bolts and small hardware• Teflon coatings on nut, bolts, small hardware and

brackets• Silicone Rubber Insulators:

– Post insulators on fiberglass crossarms and – Post insulators for jumper support (trunnion top).

• Silicone Polymer housed MOV arrestors with 17” leakage distances (vs 13” for standard arrestors),

• Wax tape applied to anchor eyes and grips

Aluminized Steel aluminum extruded over steel core

Aluminized preformed grips #2aaac, 4/0aaac and 600aac

Location 2: Blue Water Hwy near Down guy graveyard – rotated 90 degrees, and taken from direction of sea breeze. Compare A and C phases to B (center) phase. Black teflon confirmed by line mechanic was flaking and

corroding off the 24” brackets. Why?

HARDWARE COATINGS:1) HOT DIP GALVANIZED

STUD BOLTS

2) BLACK TEFLON COATED 5/8 INCH BOLT

4) STAINLESS STEEL 5/8 INCH BOLT

3) ZINC-SILICATE FLAT WASHER

Inorganic Zinc Silicate Coating

ZINC-SILICATE on 2 x 2 inch flat washer, 13/16 inch hole

Paint - Teflon

Post Hurricane “IKE”Fiberglass Deadend X-arms

Polymer DE and Post Insulators

Post Hurricane IKE: 5’ Tangent Fiberglass X-arms

Silicone rubber polymer line post insulators 240 kV CIFO, 34”leakage distance

MOV Arrestors with Minimum of 17 inch housing creep, and stainless steel studs, nuts, and washers.

TRIAL-Trenton Wax-tape installation. STEP 1: Wire brush cleaning of dirt , rust, scale.

STEP 2: Apply Temcoat 3000 primer to ensure moisture/air barrier exists.

STEP 3-Wrap with wax-tape product. Photos below-finished guy assembly. Same product used in

petrochemical industry to wrap pipelines.