coating & lining of tanks

PAINTING — COATING AND LINING OF STORAGE TANKS

FEBRUARY 1993 PAGE 1 OF 32 EGE 35-B-2 — 1993

TABLE OF CONTENTS

1. Scope 4.4 Special Service Conditions2. References 5. Tank Interiors3. General 5.1 Need For a Lining

3.1 General Requirements 5.2 Use of Tank Linings3.2 Exterior Surfaces 5.3 Types of Linings3.3 Interior Surfaces 5.4 Lining Selection3.4 Chemical Exposure 5.5 Surface Preparation3.5 Seam Sealing 5.6 Lining Application3.6 Painting Safety 5.7 Lining Thickness3.7 Nonferrous Surfaces 5.8 Lining Inspection

4. Tank Exteriors 6. Tank Identification and Marking4.1 Surface Preparation 7. Mobil Trademark4.2 Prime Coats 8. Coating Index and Lining4.3 Maintenance Painting

1. SCOPE

This Guide covers protective coating systems for storage tanks. This Guide does not include paintingprocedures for chemical exposures. For any other tank service not discussed in this Guide,recommendations shall be obtained from Mobil Technology Company (MTC), Facilities Group.

2. REFERENCES

The following publications form a part of this Guide. Unless otherwise specified herein, use the latestedition.

Mobil Engineering Guides

EGE 35-B-1 Painting — General RequirementsEGE 35-B-10 Painting — Manufacturing FacilitiesEGE 35-B-80 Painting — Seam Sealing of Riveted or Bolted TanksEGS 1060 Cathodic Protection of Aboveground Storage TanksEGS 266 Existing Tank Inspection, Repair, Alteration, and Testing

API (American Petroleum Institute) Recommended Practices

RP 2003 Protection Against Ignitions Arising Out of Static, Lightning, and Stray CurrentsRP 652 Lining of Aboveground Petroleum Storage Tank Bottoms

Code of Federal Regulations

29 CFR 1910 Title 29, Part 1910: Occupational Safety and Health Administration (OSHA) Standards (Labor)

MOBIL ENGINEERING GUIDE

EGE 35-B-2 — 1993 PAGE 2 OF 32 FEBRUARY 1993

SSPC (Steel Structures Painting Council) Publications

PA 2 Measurement of Dry Paint Thickness with Magnetic GagesVIS 1 Visual Standard for Abrasive Blast Cleaned Steel

Steel Structures Painting Manual, Volume 2, Systems and Specifications

SP 1 Solvent CleaningSP 3 Power Tool CleaningSP 5 White Metal Blast CleaningSP 6 Commercial Blast CleaningSP 7 Brush-off Blast CleaningSP 10 Near-White Blast Cleaning

NACE (National Association of Corrosion Engineers) Standards

RP0287 Field Measurement of Surface Profile of Abrasive Blast CleanedSteel Surfaces Using a Replica Tape

TM0175 Visual Standard for Surfaces of New Steel Centrifugally BlastCleaned with Steel Grit and Shot

3. GENERAL

3.1 General Requir ements

The procedures followed in the painting of storage tanks shall be in accordance with the requirements ofEGE 35-B-1 for exposure environment, surface preparation, application, and inspection. For any other tankservice not discussed by this Guide, recommendations shall be obtained from the MTC Facilities Group.

The terms for exposure conditions, as used in this Guide and in project specifications, are defined in thisSection in order of severity. They are:

(a) Mild Exposure — Areas where surfaces normally are subjected to very low humidity. Interiors ofbuildings and enclosures are generally considered to be subjected to mild exposure conditions.

(b) Normal Exposure — Areas where surfaces are subjected to normal relative humidity (30 percentto 65 percent) and no chemical environment.

(c) Severe Exposure — Areas where surfaces usually are moist or are exposed to condensation,frosting, sporadic water immersion, or high relative humidity (greater than 65 percent).

(d) Chemical Exposure — Areas where surfaces are exposed to liquid spillage or chemical vapors thathave a detrimental effect on the surface material.

3.2 Exterior Surfaces

The method of surface preparation, minimum number of coats, minimum dry-film thickness, colors, andtypes of paint used for shop and field painting shall be in accordance with the requirements of Sections 4and 8 and Tables 1 and 2 of this Guide and with the exposure conditions given in the project specifications.Maintenance painting shall conform to the requirements of this Guide, Sections 4 and 8; EGE 35-B-1,Section 8; and/or the project specifications, which stipulate exposure conditions. EGE 35-B-10, Tables 1through 3, include descriptions of coating systems available for fire protection equipment. OSHArequirements (29 CFR 1910) or other applicable code or standard for safety colors shall be followed.



Lead-based paints shall not be applied to the exterior surfaces of storage tanks.

3.3 Interior Surfaces

The method of surface preparation, minimum number of coats, recommended dry-film thickness, and typesof paint used shall be in accordance with the requirements of Sections 5 and 8 of this Guide.

3.4 Chemical Exposure

This Guide does not include painting procedures for chemical exposures. Painting recommendations forall such environments shall be obtained from Mobil Technology Company, Facilities Group.

3.5 Seam Sealing

When seam sealing of riveted or bolted tanks is necessary because of leakage at seams, the requirementsof EGE 35-B-80 shall apply.

3.6 Painting Safety

All painting shall be accomplished in accordance with local governmental regulations. Blasting is consideredhot work. Any storage tank to be blast cleaned requires approval from the local safety group. Compliancewith safety measures outlined in API RP 2003 and with plant safety rules is required when storage tanks areblast cleaned while in service.

3.7 Nonferrous Surfaces

Galvanized or aluminum surfaces shall not normally be painted unless safety color code markings arerequired. Galvanized surfaces may be painted where previous experience indicates the need exists. Tables1 and 2 cover painting requirements for galvanized surfaces.

4. TANK EXTERIORS

4.1 Surface Preparation

4.1.1 Abrasive blast cleaning is the preferred method of surface preparation and shall be used exceptin hazardous areas where blast cleaning is not permitted.



TABLE 1EXTERIOR EXPOSURE

MILD AND NORMAL EXPOSURE CONDITIONS (Note 4)(Colors are an approved part of the Mobil Identity Program.)

Prime Coats (Note 1)

SurfacePreparation

First Coat Finish Coats RemarksCoat (Note 2) (Notes 1 and 5) Color (Note 3)

Second

CONE-ROOF AND DOME-ROOF TANKS

Power tool Nonlead Nonlead Volatile products: Gasoline, White a. One spray coat of high-build

or

Commercial Epoxy Nonvolatile distillates: Diesel oil, Mobilblast mastic heating oil, etc. Roof and shell Beige

primer primer MTBE, naphtha, solvents, etc. alkyd tank white may beRoof and shell courses substituted for two coats of(includes fittings): Tank white tank white alkyd.alkyd (2 coats)

a

courses (includes fittings):Alkyd enamel (1 coat)

Residual black oils: Bunker C,No. 6 fuel, road oil, etc. Entire Blacktank (including fittings): Alkydenamel (1 coat)

HORIZONTAL TANKS

Power tool Nonlead Nonlead Volatile products: Propane, White See remark (a).

or

Commercial Epoxy Nonvolatile products: Lube oil, Mobilblast mastic diesel oil, etc. Beige

primer primer butane, LPG, etc.Tank and fittings: Tank whitealkyd (2 coats)

a

Tank and Fittings: Alkyd(1 coat)

Legs, bases, saddles: All BlackproductsMetal: Alkyd (1 coat)Concrete: Do not paint.

OPEN-TOP, FLOATING-ROOF TANKS: ROOF AND STIFFENING RINGS (WINDGIRDERS)b

Power tool Epoxy Epoxy mastic (1 coat) White b. Windgirder shall be same

or

Near-white Epoxy None High-build epoxy (1 coat) Whiteblast zinc rich

mastic color as shell.

OPEN-TOP, FLOATING-ROOF TANKS: SHELL

Power tool Nonlead Nonlead primer Upper-courses (includes White See remark (a).

or Beige

Commercial Epoxyblast mastic

primer fittings): orTank white alkyd (2 coats) or

a

alkyd (1 coat)Mobil

TABLE 1 — Contd




SurfacePreparation

First Coat Finish Coats RemarksCoat (Note 2) (Notes 1 and 5) Color (Note 3)

Second

SPHERES AND SPHEROIDS

Power tool Nonlead Nonlead Shell: Tank white alkyd White See remark (a).

or

Commercial Epoxy Spheroid skirt: Alkyd Blackblast mastic

primer primer (2 coats)a

Sphere legs: Fireproofed—prime paintshould becompatiblewithfireproofing.

TANK ACCESSORIES: ALL TANKS

Commercial Nonlead Nonlead primer Platform, walkways, handrails, Lemon Yellow c. Platforms, etc., may be leftblast primer stairs, ladders, ladder cages, unpainted if galvanized.

or

Epoxy Tank valves, gage supports:mastic Same as tank background.

bridges: Alkyd gloss enamel (2coats)

c

Piping: Alkyd (1 coat) BeigeMobil

GALVANIZED SURFACES

Solvent clean Metal None Platforms, walkways, handrails, Lemonand brush primer stairs, ladders, ladder cages, Yellowblast bridges: Alkyd enamel

NOTES TO TABLE 1:

1. For specific recommendations on paint type, see Tables 6 and 7.2. For mild exposure conditions, the second prime coat may be omitted.3. Superscript letters (a, b, c) used throughout the Table refer to the remarks in this column.4. See Paragraph 4.3 for maintenance painting requirements.5. On roofs painted white, an area 0.6 m (2 ft) in diameter surrounding gage hatches shall be painted black with one coat of an alkyd paint, such as

Valspar V20-J-5 or equivalent.



TABLE 2EXTERIOR EXPOSURE

SEVERE EXPOSURE CONDITIONS(Colors are an approved part of the Mobil Identity Program.)


SurfacePreparation

First Second Finish Coats RemarksCoat Coat (Notes 1, 4, and 5) Color (Note 2)

CONE-ROOF AND DOME-ROOF TANKS

Near-white Epoxy None Volatile products: Gasoline, Whiteblast zinc rich MTBE, naphtha, solvents, etc.

Roof and shell courses: High-build epoxy (1 coat)

Nonvolatile products: Diesel oil, Mobilheating oil, etc. Roof and shell Beigecourses: High-build epoxy (1coat)

Residual black oils: Bunker C, BlackNo. 6 fuel, road oil, etc. Entiretank (includes fittings): High-build epoxy (1 coat)

HORIZONTAL TANKS

Near-white Epoxy None Volatile products: Propane, Whiteblast zinc rich butane, LPG, etc. Tank and

fittings: High-build epoxy(1 coat)

Nonvolatile products: Lube oil, Mobildiesel oil, etc. Tank and fittings: BeigeHigh-build epoxy (1 coat)

Legs, bases, saddles: Allproducts BlackConcrete: Do not paint.Metal: High-build tank liningepoxy (1 coat)

OPEN-TOP, FLOATING-ROOF TANKS: ROOF AND STIFFENING RINGS (WINDGIRDERS)a

Power tool Epoxy Epoxy mastic (1 coat) White a. Windgirder shall be same

or

Near-white Epoxy None High-build epoxy (1 coat) Whiteblast zinc rich

mastic color as shell.

OPEN-TOP, FLOATING-ROOF TANKS: SHELL

Near-white Epoxy None Upper-courses (includes Whiteblast zinc rich fittings): High-build epoxy or

(1 coat) MobilBeige



TABLE 2 — Contd


SurfacePreparation

First Second Finish Coats RemarksCoat Coat (Notes 1, 4, and 5) Color (Note 2)

SPHERES AND SPHEROIDS

Near-white Epoxy None Shell: High-build epoxy Whiteblast zinc rich (1 coat)

Spheroid skirt: High-build tank Blacklining epoxy (1 coat)

Sphere legs: Fireproofed—prime paintshould becompatiblewithfireproofing.

TANK ACCESSORIES: ALL TANKS

Near-white Epoxy None Platform, walkways, handrails, Lemon b. Platforms, etc., may be leftblast zinc rich stairs, ladders, ladder cages, Yellow unpainted if galvanized.

bridges: High-build epoxy (1spray or 2 brush coats)b

Tank valves, gage supports:Same as tank background.

Piping: High-build epoxy(1 coat) Mobil

Beige

GALVANIZED SURFACES

Solvent clean Epoxy None Platforms, walkways, handrails, Lemonand brush mastic stairs, ladders, ladder cages, Yellowblast bridges: High-build epoxy

NOTES TO TABLE 2:

1. For specific recommendations on paint type, see Tables 6 and 7.2. Superscript letters (a, b) used throughout the Table refer to the remarks in this column.3. See Paragraph 4.3 for maintenance painting requirements.4. On roofs painted white, an area 0.6 m (2 ft) in diameter surrounding gage hatches shall be painted black with one coat of an alkyd enamel, such

as Valspar V20-J-5, or equivalent.5. If a high gloss is required for aesthetics or it is the normal practice of the plant to finish coat tanks with a high gloss, the epoxy finish coat shown

above can be topcoated with a urethane enamel, such as Valspar 40 series, or equivalent (in the appropriate color).



4.1.2 A "silica-free" abrasive material shall be used. Personnel performing the work shall wear properair breathing and safety equipment. A "grit" abrasive is preferred to a "shot" abrasive. A "grit" abrasive willgive a better anchor pattern for coating than will a "shot" abrasive.

4.1.3 Where the existing paint system is red lead/alkyd and blast cleaning is not permitted, hand toolcleaning, hand sanding, or chemical rust removal compounds may be specified. The prime coat and themethod of application shall be compatible with the surface preparation. Environmental regulations shouldbe observed when removing lead-based paints. Removal of lead-based products should be done inaccordance with all appropriate laws and regulations. For minor repairs to a red lead/alkyd system, spotblasting and priming with a compatible nonlead-based primer should be conducted. Removal of the entirelead-based system should be considered.

4.2 Prime Coats

4.2.1 All steel tank surfaces shall be primed in accordance with the requirements shown in Tables 1 and2.

4.2.2 An epoxy mastic primer can, with Mobil approval, be used as a primer over marginally preparedsteel surfaces. The epoxy mastic primers such as Valspar Alumapoxy (V75-A-1) and Valspar Val-ChemEpoxy Mastic (V75-W-9, V75-D-7), or equivalent, can be topcoated with a high-build epoxy.

4.3 Maintenance Painting

It is acceptable to utilize the same generic coating system for maintenance painting of an existing paintedsurface. However, it is generally best to perform maintenance painting prior to damage to the existingprimer. EGE 35-B-1, Section 8, shall be referred to when deciding the coating requirements for maintenancepainting.

4.3.1 The surface to be painted shall be cleaned by blasting, power tools, hand tools, or solvents, or bya combination of these. All grease, oil, dirt, foreign matter, and rust — as well as loose, cracked, brittle, ornonadhering paint — shall be removed.

4.3.2 New prime and/or finish coatings shall be checked or tested for compatibility with the paints theyare to cover to ensure that the existing coating will not lift or wrinkle.

Compatibility between paints of various manufacturers should be considered prior to paint selection. TheMTC Facilities Group should be contacted for guidance on compatibility.

4.3.3 When the existing coating is the alkyd system (Table 1), the maintenance painting primer shall bean epoxy mastic, such as Valspar V75-W-9 or equivalent. The topcoat shall be either a high build epoxysuch as the Valspar V89 Series or equivalent or a urethane enamel such as Valspar V40 Series orequivalent.

4.3.4 When the existing coating is the zinc-rich epoxy/epoxy system (Table 2), the maintenance paintingprimer shall be an epoxy mastic such as Valspar V75-W-9 or equivalent. The topcoat shall be either a highbuild epoxy such as the Valspar V89 Series or equivalent or a urethane enamel such as Valspar V40 Seriesor equivalent.

4.4 Special Service Conditions

4.4.1 Painting of roofs and shells of insulated or fireproofed tanks shall be done as follows.Temperatures shown below relate to actual metal surface temperature.



(a) Up to 110ºC (230ºF) — Commercial blast clean the surface and topcoat with two coats of aphenolic alkyd zinc phosphate primer such as Valspar Chromox Primer (V13-R-28), or equivalent.When, for safety reasons, blast cleaning is not permitted, a good power tool cleaner can be substituted.An alternative system includes the preferred blast cleaning with a coat of an epoxy mastic such asValspar V75 Series, or equivalent.

(b) From 110ºC to 180ºC (230ºF to 355ºF) - Commercial blast clean the surface and topcoat with onecoat of an inorganic ethyl silicate such as Valspar MZ-7 Inorganic Zinc Rich (13-F-12), or equivalent.

4.4.2 The coating of refrigerated and insulated single-wall tanks down to a service temperature of !18ºC(0ºF) shall be achieved by application of an epoxy zinc such as Valspar MZ-4 (13-F-4), or equivalent.

4.4.3 Uninsulated hot product storage tanks operating in the 66ºC to 177ºC (150ºF to 350ºF) range shallbe primed with one coat of an epoxy zinc rich such as Valspar MZ-4 (13-F-4), or equivalent, applied overa white metal blast-cleaned surface. The finish coat shall be a silicone/acrylic such as ValsparHeat-Resisting Silicone/Acrylic (V37-F-209), or equivalent.

4.4.4 The use of a coating on the underside of a tank bottom is not permitted, unless approval has beenobtained from MTC Facilities Group.

5. TANK INTERIORS

5.1 Need For a Lining

The need for an internal tank lining in an aboveground storage tank is based upon several considerations.These include:

! Internal corrosion prevention.! Product cleanliness.! Alternate services and upset conditions.! Federal, state, and local regulations.

5.2 Use of Tank Linings

The proper selection and application of tank linings can prevent internal corrosion of the steel tank bottom,tank shell, and/or the underside of the tank roof. The external surfaces of the tank are protected fromcorrosion by means of coatings for the tank shell and roof as covered by Section 4 of this Guide. Theexternal or underside surfaces of the tank bottom are protected from corrosion by means of cathodicprotection as covered in EGS 1060.

5.2.1 Tank Bottom Linings

Generally, most products stored in tanks are not corrosive to steel. In many cases however, corrosiveconditions such as accumulation of water or sludge occur on the bottom, causing the need for a tank bottomlining. A more detailed discussion of tank bottom corrosion mechanisms can be found in API RP 652.

Tank bottom linings shall be utilized for situations where product contamination could result if corrosionoccurs (i.e., jet fuel, etc.). Also, tank bottom linings shall be used when water accumulation that will causecorrosion is expected (i.e., crude oil, etc.) and/or where the product stored is corrosive to the tank bottomsteel.



5.2.2 Tank Shell Linings

Generally, most products that will come in contact with the shell are not corrosive to steel. However,corrosion can occur on the shell above the liquid level when the product stored contains sulfur compoundsthat can combine with moisture condensation to form corrosive acids. Also, only limited corrosion wouldbe expected on the tank shell where the surface will remain in constant contact with the stored product.

Tank shell linings shall be utilized for situations where product contamination could result if corrosion occurs(i.e., jet fuel, etc.), the stored product is corrosive to the tank steel, and/or for tanks storing sulfur-containingproducts that can combine with moisture condensation to cause a corrosive environment.

5.2.3 Tank Roof Coating

Generally, most products that will come in contact with the tank roof underside are not corrosive to steel.However, corrosion can occur on the fixed roof tanks where the product stored contains sulfur compoundsthat can combine with moisture condensation to form corrosive acids. Also, only limited corrosion wouldbe expected on the underside of steel floating roofs where the surface will remain in constant contact withthe stored product.

Tank roof underside coatings shall be utilized for fixed roof tanks where product contamination could resultif corrosion occurs. Also, coatings shall be used for situations where stored product contains sulfurcompounds that can cause corrosion of the tank roof underside (i.e., crude oil, marine diesel, etc.).

5.2.4 Tank Lining Considerations

Tanks may have design and fabrication features that would make the application of a lining impractical orthat would seriously jeopardize the integrity of a lining. For example, internal steam coils, which are usedto heat a product to maintain a desirable viscosity, limit accessibility to the tank bottom during surfacepreparation and application of the lining. As a result, a good quality installation may be difficult to achieve.In service, steam coils create local areas where the temperature can be much greater than that of the bulkproduct. The resulting thermal effects on a tank bottom lining may cause localized failure by blistering orby cracking.

5.3 Types of Linings

Tank linings can be divided into two classes: thin films, 500 µm (20 mil) or less, and thick films, greater than500 µm (20 mil). The thin-film linings can be applied to the tank bottom, tank shell, and/or roof underside.The use of the thick-film linings other than the glass flake polyester are typically limited to application to thetank bottom.

Linings may be applied to the tank internals when they are first constructed or they may be installed aftersome period of service.

5.3.1 Tank Bottom Linings

Thin-film linings can be applied to new tanks and to tanks that have experienced minimal bottom corrosion.Typically, thick-film linings are only used when a tank bottom has suffered severe corrosion. Information onminimum allowable tank bottom thickness is covered in EGS 266.

Tank bottom linings generally cover the entire tank bottom and extend 450 to 600 mm (18 to 24 in.) up thetank shell. The design of the lining should follow the manufacturer's recommendations. Thin-film liningsare generally applied in two or three coats to achieve the desired dry-film thickness. For thick-film linings,



one to four coats may be required to obtain the desired lining thickness. Thick-film or thin-film linings shouldnot be used to prevent tank bottom leakage due to continuing soilside corrosion.

5.3.2 Tank Shell Linings

Thin-film linings are used most often to protect the shell against corrosion. They do not have to be the samelining material used to coat the tank bottom but must be chemically resistant to the stored product. Also,the tank shell lining must be chemically compatible with the tank bottom lining since the shell lining may beused to overcoat the bottom lining up to 450 to 600 mm (18 to 24 in.) of the tank shell. The only thick-filmlining that can be used for the tank shell is the glass flake reinforced polyester type materials.

5.3.3 Tank Roof Coatings

Thin-film coatings are used to protect the roof underside from corrosion. The coating used should becompatible with the product stored in the tank. The same coating used for the tank shell and/or tank bottomis generally acceptable for the tank roof.

5.4 Lining Sel ection

Once it has been determined that a lining will be used, the type of coating can be determined from Tables3 and 4. Table 3 presents the types of linings that can be selected and Table 4 shows typical dry-filmthickness and temperature limitations of the particular coating type. The information in Tables 3 and 4 isindustry accepted. The chemical compatibility, dry-film thickness, and temperature limitations for any paintproduct should be confirmed by the paint manufacturer prior to product use.



TABLE 3COATING SELECTION

(Note 1)

Coating Reference Number (Note 2)

Service Thin-Film Coating Thick-Film Coating

Potable water 1,2 4,5,6,7Utility water 1,2,3 4,5,6,7Wastewater 1,2,3 4,5,6,7Demineralized water 1 4,5,6Crude oil 1,2 4,5,6,7Fuels (low aromatic) 1,2 4,5,6,7Fuels (high aromatic or with MTBE) 1 4,5,6Ethanol 1 4,5,6MTBE 1 4,5,6

NOTES:

1. The actual choice of possible products should be based on specific operating conditions, economics, availability of products, andqualified applicator, among other factors.

2. Refer to Table 4 for the description of the coating reference numbers.

TABLE 4TYPICAL COATING SYSTEMS

Typical Total Dry-Film Thickness (DFT) Temperature Limits (Note 1)

µm (mil) ºC ºF

1. Epoxy phenolic (Note 2) 250 — 350 10 — 14 82 — 104 180 — 2202. Epoxy (Note 2) 250 — 350 10 — 14 60 — 71 140 — 1603. Coal tar epoxy (Note 2) 300 — 400 12 — 16 49 — 66 120 — 1504. Glass flake reinforced 750 — 1000 30 — 40 66 1505. Vinyl ester reinforced 1250 — 2750 50 — 110 82 — 93 180 — 2006. Polyester reinforced 1250 — 2750 50 — 110 49 — 60 120 — 1407. Epoxy reinforced 1250 — 2750 50 — 110 60 — 71 140 — 160

NOTES:

1. The temperature limit refers to the actual temperature the lining will or could be subjected to.2. See Tables 6 and 7 for examples of acceptable products.



5.5 Surface Preparation

5.5.1 Interior surfaces to be painted shall be prepared by blast cleaning to a near-white metalspecification (SSPC SP 10) or to a white metal blast clean specification (SSPC SP 5) depending on therequirement of the coating chosen.

5.5.2 Welds should be inspected before and after blast cleaning. All sharp edges and protrusions shouldbe ground to provide a smooth surface that can be completely and uniformly covered with the lining material.Sharp edges and protrusions may be caused by such things as weld spatter, sharp weld crests, undercuttingof the weld, arc burns, erection clips, plate joints, burrs, and gouges. Chipping, followed by grinding, canbe used to remove sharp edges. Early lining failure can result if sharp edges and protrusions are notproperly removed. A suggested minimum radius of 3.2 mm (0.125 in.) for grinding work should beconsidered

5.5.3 The surface preparation abrasive should be selected to produce the necessary surface profile forthe lining to be applied. The coating manufacturer’s recommendation for surface profile must be achievedin order to optimize the mechanical adhesion of the lining to the steel tank bottom. The surface profilerequired for linings is typically 37 to 63 µm (1.5 to 2.5 mil) and generally increases with the thickness of thelining.

5.5.4 Abrasive blasting should not be performed if the temperature of the steel surface is less than 3ºC(5ºF) above the dew point or if the relative humidity is greater than 80 percent.

The surface to be coated should have the specified surface preparation at the time the lining is applied. Ifthe surface is degraded or contaminated subsequent to surface preparation and prior to lining application,the surface should be restored before lining application.

Since freshly blasted surfaces are subject to immediate corrosion, particularly in areas of high humidity orsalt atmospheres such as marine environments, no more surface shall be blast cleaned than can be primecoated before visible or detrimental rerusting occurs. Blasted surfaces shall be prime coated no later thanat the end of the same workday.

To eliminate the problem of high humidity, use of dehumidification equipment should be considered.

5.5.5 The abrasive and compressed air supply used for abrasive cleaning of tank internal surfacesshould be free of contaminants such as water-soluble salts, dirt, clay, oil, and grease. If present in theblasting abrasive, small amounts of these contaminants may be delivered to the steel surface during thecleaning operation. These contaminants will reduce the useful life of the lining.

5.6 Lining Application

The application of a lining shall be in accordance with manufacturer's recommendations. Manufacturer'srequirements on temperature and humidity during application shall be followed.

5.7 Lining Thickness

Insufficient film thickness will not provide adequate coverage for protection. Excessive film thickness cancompromise coating adhesion and film integrity. The lining thickness shall be in accordance with the liningspecification and manufacturer's recommendations.

5.8 Lining Inspection

The lining work shall be inspected during application and upon completion of the work.



5.8.1 All inspectors should be either NACE certified or persons who have demonstrated a thoroughknowledge of coating and lining practices.

5.8.2 Surface cleanliness and profile shall be verified prior to application of any coating.

SSPC VIS 1 provides reference photographs and NACE TM0175 provides steel reference panels sealedin clear acrylic plastic that may be used to visually assess surface cleanliness. NACE RP0287 provides amethod of measuring surface profile. Other types of profile comparators are available from SSPC andcoating instrument suppliers.

5.8.3 Soon after coating application, wet-film thickness measurements should be made. After thecoating has cured sufficiently to allow handling, dry-film thickness measurements should be made inaccordance with SSPC PA 2. Visual examination of the coating shall be conducted after curing. Particularattention should be given to note the presence of surface irregularities, such as runs, sags, alligatoring,foreign material, dirt, etc.

5.8.4 The integrity of all coating surfaces shall be verified by using an acceptable low-voltage,wet-sponge holiday detector, such as the Tinker Rasor Model M-1, Elcometer Model DG-2150, or theirequivalents. Any pinholes or other defects detected shall be marked and subsequently repaired to yield adefect-free surface.

6. TANK IDENTIFICATION AND MARKING

6.1 Identification numbers shall consist of numerals in the standard Mobil Alphabet (see Figure 1) paintedon a background disk. The colors, sizes, spacing, and location of the numerals and background shallconform to the requirements given in Paragraphs 6.1.1 through 6.1.4.

6.1.1 Colors

(a) For Tank Shells Painted Mobil Beige or Black - Numerals shall be Century Red (Valspar CoatingV20-R-101 or equivalent) on a White (Valspar Coating V20-W-2 or equivalent) disk.

(b) For Tank Shells Painted White - Numerals shall be White on a Century Red disk.

6.1.2 Sizes

When the tank identification numerals contain several digits, their height shall be reduced to fit attractivelyinto the background disk. Numerals shall be sized in accordance with tank heights, as follows:

(a) For tanks 9 m (30 ft) and more in height (read "diameter" for "height" of spheres and horizontaltanks), all three-digit numbers shall be three-eighths of their background disk diameter in height. Whenpractical, numerals shall be 900 mm (36 in.) high, and the background disk shall be 2.4 m (8 ft) indiameter. All four-digit numerals shall be one-quarter of their background disk in height. (See Figure4 for typical layout.)



(b) For tanks less than 9 m (30 ft) in height (read "diameter" for "height" of spheres and horizontaltanks), the height of all numerals shall be one-third of the disk diameter (when practical) and the diskdiameter shall be one-quarter of H.

NOTE: Definitions of H for:Horizontal tanks and spheres - the diameter of the tank or sphere.Dome-roof tanks - the vertical distance from the tank bottom to the line of transition of shell to roof.Cone-roof, open-top - the vertical distance from the tank bottom to the top angle of the shell.

(c) For tanks with a height-to-diameter ratio greater than 1.5:1, disks shall be one-half the diameterof the tank but not less than 1.2 m (4 ft) or more than 2.4 m (8 ft) in diameter. Disks shall be positionedwith their centerlines at two-thirds the tank height, but not more than 3 m (10 ft) below the top of theshell.

6.1.3 Spacing

A grid system over the numerals is illustrated in Figures 2A through 2E. The grids are composed of 75 mm(3 in.) squares when the numerals are 900 mm (36 in.) high. For other numeral heights, the square grid overthe numerals should be used as a guide for enlargement to the desired size. If suitable equipment isavailable, it is preferred that the numerals be enlarged photographically or by optical projection. The spacingbetween numbers shown in Figures 2A through 2E is not the spacing specified in Table 5.

In Table 5, where the proper spacing between numerals is given, a unit of spacing is equal to the gridspacing of Figures 2A through 2E. The first numeral is found in the left-hand column and the followingnumeral is found across on the top line.

TABLE 5NUMERICAL SPACING UNITS

FOLLOWING NUMERAL

0 1 2 3 4 5 6 7 8 9

0 1 1 11/2 1/2 1/2 1/2 1/2 1/2 1/2

1 1 1 1 1 1 1 1 1 1 1

2 1 1 1 11/2 1/2 1/2 1/2 1/2 1/2

3 1 1 1 1 1 1 1 11/2 1/2

4 1 1 1 1 1 1 0 11/2 1/2

5 1 1 1 1 1 1 11/2 1/2 1/2

6 1 1 1 1 1 0 11/2 1/2 1/2

7 1 0 11/2 1/2 1/2 1/2 1/2 1/2 1/2

8 1 1 1 1 1 11/2 1/2 1/2 1/2

9 1 1 1 1 0 11/2 1/2 1/2 1/2



Example - To make up the number 472:

The spacings between 4 and 7, and 7 and 2 are needed. Find 4 in the left column and read across to thecolumn headed by 7. The unit answer is 0.

To space 72, find 7 in the left column and read across to the column headed by 2, which shows a unit spaceof 1/2. The spacing units are measured from the extreme left- and right-hand edges of the numerals, asshown in Figure 3.

6.1.4 Location

(a) Horizontal Tanks - The identification number shall be located on one of the tank heads with the diskcenterlines concentric to the head axis.

(b) Spheres - The horizontal centerline of the disk shall be along the horizontal axis of the spheres.

(c) Dome-Roof Tanks - The distance of the horizontal centerline of the disk below the line of transitionof the shell to the roof of the tank shall be 3 m (10 ft) for tanks 9 m (30 ft) and more in diameter and one-third H for tanks less than 9 m in diameter.

(d) Cone-Roof and Open-Top Tanks - The distance of the horizontal centerline of the disk below thetop of the tank shell shall be 3 m (10 ft) for tanks 9 m (30 ft) and more in diameter and one-third H fortanks less than 9 m in diameter.

The location of primary identification numbers on tanks within a group should be consistent; that is, allidentification numbers should face the tank farm road. Where desirable from an operational standpoint, asecond identification number of the same size may be located where convenient.

Smaller secondary numbers (where required) may be located on the tank at suction lines or fill lines, or both.A white disk, 300 mm (12 in.) in diameter with 100 mm (4 in.) high Century Red numbers, shall be centeredbetween the suction and discharge lines when they are close together. When these lines are widelyseparated, the disk shall be centered above a single line midway between the top of these lines and the topof the black bottom band or top of first shell course.

6.2 Certain structural aspects of the tank, such as excessive height-to-diameter ratio, the location andnumber of stiffening rings on an open-top tank, or the height of the vertical shell section of a vapor-dometank, may preclude the sizing and location of the identification number as specified in Paragraph 6.1. In thiscase, the identification number shall be proportionately reduced in size and located to suit the tank condition.In a battery of such tanks, the modifications shall be consistent. For a neat appearance, the individualidentification marks shall be aligned with regard to height.

6.3 A typical layout for a tank identification number located on a cone-roof tank 9 m (30 ft) or more indiameter is shown in Figure 4. The general principles regulating the layout of the numerals and disk shallapply to all types of tanks.

6.4 Should additional identification be required by local authorities, characters shall be in the standardMobil Alphabet (see Figure 1), and the color system shall comply with Paragraph 6.1.1.



Tank Diameter Greater Than 9 m (30 ft)



6.5 Storage tanks shall be inscribed with the date of painting and/or cleaning. Letters and numerals shallbe painted on the tank in red with an alkyd enamel such as Valspar V20-R-101 Bulletin Coating orequivalent, 25 mm (1 in.) high, with 3 mm (1/8 in.) stroke characters. Inscriptions shall be as follows:

(a) "SHELL PAINTED (date) " shall be painted on the shell 200 mm (8 in.) above the edge ofthe manhole cover closest to the product inlet and outlet nozzles. The inscription shall straddle thevertical centerline of the manhole.

(b) "ROOF PAINTED (date) " shall be painted 25 mm (1 in.) above the inscription given in Item(a).

(c) "CLEANED (date) " shall be painted on the manhole cover 150 mm (6 in.) above thecenterline.

(d) "INTERIOR LINED (date) " shall be painted 25 mm (1 in.) above the inscription given inItem (b).

The date in each inscription shall consist of the month and year only, and both shall be indicated in numbers;for example: 10-92. The particular paint product name descriptions shall also be included.

7. MOBIL TRADEMARK

7.1 Tanks in prominent locations may have the Company trademark or logo (in the form of the word"Mobil") painted on their shells. The tank identification number shall be painted on the side opposite thetrademark. In a given facility, the Mobil trademark shall be limited to one per side, or exposure, of thatfacility.

7.2 The Mobil trademark or logo shall be painted in Century Blue (Valspar Coating V20-B-101 orequivalent) and Century Red (Valspar Coating V20-R-101 or equivalent), in accordance with the grid andrequirements shown in Figure 5. This trademark shall be painted only on Mobil Beige or White tanks. Sizeand location of the trademark shall be in accordance with the requirements of Figure 6.

7.3 For Company identity, the Mobil trademark should be painted only on cone-roof, or open-top tanks.

7.4 Certain structural aspects of a tank, such as an excessive height-to-diameter ratio, the location andnumber of stiffening rings on an open-top tank may preclude the sizing and location of the trademark asspecified in Paragraph 7.2. In that case, the trademark shall be proportionately reduced in size and locatedto suit the tank condition.

8. COATING INDEX AND LINING

8.1 Tables 6 and 7 key the generic coatings specified in this Guide and the acceptable dry-film thicknessrange per coat required for each product. The maximum dry-film thickness shall not be exceeded by morethan 25 percent.

8.2 Tables 6 and 7 reference the use of Valspar Corporation paint products, or equivalents. Contact theMTC Facilities Group for acceptable equivalents. When a Valspar Corporation equivalent paint product isapproved and used, the completion of the data form shown in Table 8 is required. Completed forms shouldbe returned to the MTC Facilities Group. The information included in this form will be used to develop aperformance data base to determine the effectiveness of a particular company’s products.



8.3 Compatibility between various manufacturers’ paints should be considered prior to paint selection. TheMTC Facilities Group should be contacted for guidance on compatibility.

8.4 The generic coatings identified in this Guide are based on Mobil field experience. The MTC FacilitiesGroup shall approve equivalence of manufacturers’ products that have not previously been adequatelyevaluated by Mobil.



TABLE 6UNDERCOAT INDEX

Generic Dry-Film ThicknessRecommended

Product Examples* Fm mil Color

Epoxy zinc Valspar 13-F-4 50 to 75 2.0 to 3.0 Gray Greenrich or equivalent

Nonlead Valspar 13-R-29 38 to 50 1.5 to 2.0 Orangeprimer or equivalent

Metal primer Valspar V89-W-71 50 to 75 2.0 to 3.0 Whiteor equivalent

Coal tar Valspar V64-J-5 175 to 200 7.0 to 8.0 Dark Redprimer or equivalent

Tank lining Valspar V78-D-7 100 to 125 4.0 to 5.0 Light Buffhigh-build or equivalentepoxy

Epoxy mastic Valspar V75-A-1 125 to 200 5.0 to 8.0 Aluminumor equivalent

Epoxy mastic Valspar V75-W-9 125 to 200 5.0 to 8.0 Whiteor equivalent

Epoxy mastic Valspar V75-D-7 125 to 200 5.0 to 8.0 Whiteor equivalent

Phenolic alkyd Valspar V13-R-28 50 to 63 2.0 to 2.5 Redzinc phosphate or equivalent

Inorganic ethyl Valspar 13-F-12 75 to 100 3.0 to 4.0 Gray Greensilicate or equivalent

Epoxy phenolic Valspar V9-W-9 125 to 150 5.0 to 6.0 Whiteor equivalent

________

*See Paragraph 8.4.



TABLE 7FINISH COAT INDEX



Alkyd enamel Valspar V20-F-38 38 to 50 1.5 to 2.0 Mobil Beigeor equivalent

Alkyd enamel Valspar V20-J-5 38 to 50 1.5 to 2.0 Blackor equivalent

Tank white Valspar 12-W-3 38 to 63 1.5 to 2.5 Whitealkyd or equivalent

High-build Valspar 12-W-4 100 to 125 4.0 to 5.0 Whitealkyd tank or equivalentwhite

Epoxy mastic Valspar V75-W-9 125 to 200 5.0 to 8.0 Whiteor equivalent

Coal tar Valspar V64-J-5 200 to 250 8.0 to 10.0 Blackepoxy or equivalent

High-build Valspar V89-J-5 125 to 175 5.0 to 7.0 Blackepoxy or equivalent

High-build Valspar V78-W-9 125 to 175 5.0 to 7.0 Whitetank lining or equivalentepoxy

High-build Valspar V89-F-38 100 to 175 4.0 to 7.0 Mobil Beigeepoxy or equivalent

High-build Valspar V89-W-9 100 to 175 4.0 to 7.0 Whiteepoxy or equivalent

High-build Valspar V89-Y-21 100 to 175 4.0 to 7.0 Lemon Yellowepoxy or equivalent

Epoxy mastic Valspar V75-F-38 125 to 200 5.0 to 8.0 Mobil Beigeor equivalent

Alkyd enamel Valspar V20-B-101 38 to 50 1.5 to 2.0 Century Blueor equivalent

________

*See Paragraph 8.4.



TABLE 7 — Contd



Alkyd enamel Valspar V20-R-101 38 to 50 1.5 to 2.0 Century Redor equivalent

Alkyd enamel Valspar V20-W-9 38 to 50 1.5 to 2.0 Whiteor equivalent

Alkyd enamel Valspar V20-Y-21 38 to 50 1.5 to 2.0 Lemon Yellowor equivalent

Silicone Valspar V37-F-209 25 to 38 1.0 to 1.5 Grayacrylic or equivalent

Urethane Valspar V40 Series 38 to 50 1.5 to 2.0 Variousenamel or equivalent

Epoxy phenolic Valspar V9-D-7 125 to 150 5.0 to 6.0 Light Buffor equivalent

________

*See Paragraph 8.4.



TABLE 8APPROVED PAINT PRODUCT DATA FORM

LOCATION

DATE FORM RETURNED PERSON REPORTING DATA

UNIT

EQUIPMENT DESCRIPTION OF SURFACE PAINTED*

OPERATING TEMPERATURE OF SURFACE PAINTED

SURFACE PREPARATION SSPC-

Paint Date Weather Dry-Film How PaintProduct Applied Conditions Thickness, µm (mil) Applied

Primer

Intermediate

Intermediate

Intermediate

Topcoat

GENERAL COMMENTS

*Include equipment number (for example, T-204, T-1293).

coating & lining of tanks

Documents

painting coating

painting safety

painting of storage

tank service

b normal exposure areas

commercial blast cleaningsp

brushoff blast cleaningsp

exterior surfaces