What Makes a Tank Worthy of

an STI Label

Wayne Geyer,

STI/SPFA

September 16, 2013

Denver, Colorado

Who and What is STI/SPFA?

• Association of 180 fabricating and affiliate

companies of steel construction products – shop-

fab tanks, field erect tanks, pipe, pressure vessels

and other special fabricated products

• STI members account for nearly all of the total

shop fabricated underground steel storage tank

production capacity in North America

2012 Annual Product Awards:

Steel Fabricated Products

www.steeltank.com

Steel Fact Sheets

www.steeltank.com

What does the Steel Tank Institute do?

• UST and AST tank

technologies

• Industry standards and

recommended practices

• License manufacturers to

build tanks to STI

specifications

• Quality control

• Information resource

• Certification

4 – 50,000 Gallon

Permatanks Installed at

Northwestern Univeristy

Education, Research, & Advocacy

STI Certification Programs

• 927 Certified SP001 Aboveground

Storage Tank Inspectors

• 484 Certified Cathodic Protection Testers

• Over 130,000 sti-P3 tanks tested for

cathodic protection through WatchDog

program

• NEW: On Line Learning Program

• T*I*M Tank Integrity Management

STI Shop-Fabricated Tank Program

• > 100 tank shops licensed and inspected

• 14 tank fabrication standards

• 19 recommended practices for testing,

installation and inspection

– NEW: R111 Storage Tank Maintenance

– Under Development: SP131- UST

Inspection, Repair, & Modification

• 6 UL files with hundreds of volumes & 4

SWRI technology programs

Steel Storage Tank Standards

• Underwriters Laboratories

– UL 58: construction of the

underground steel tank and

secondary steel containment

– UL 1746: construction of

the corrosion control and

“jacketed” tank

– UL 142: construction of the

aboveground steel tank and

secondary steel containment

• Steel Tank Institute

– Uses UL 58 & UL 142 as

basis for the fabrication of

the steel primary tank

– STI Dual Wall Tank Std.

• Corrosion control

– Sti-P3: cathodic protection

– ACT-100 “composite” &

ACT-100-U urethane

– Permatank: FRP jacketed

steel tank

Steel Specifications

• UL and STI standards

specify steel requirements

– ASTM A 1011

– ASTM A 36

– Carbon Equivalency <0.53

• Steel is purchased by

fabricator in plate form or in

coil form from steel mills or

steel service centers

Steel Specification

• Steel mills carefully control composition of steel

• Carbon is added to iron to form steel. Addition of alloy and chemicals and the process in which it the steel is made gives the steel its desired properties.

Steel Specification

• Carbon is kept below 0.3%.

Higher carbon content adds

strength but reduces

weldability and

formability.

• Addition of manganese and

silicon provide added

strength.

Desirable Properties of Steel

• Yield Strength

• Tensile Strength

• Flexural Strength

• Ductility

• Hardness

• Resistance to Impact

• Formed into any

Shape and Size

Tank Shell (Barrel)

• Flat plate must be

rolled to the specified

diameter

• Each plate will be

obtained by the

fabricator with a

specific width, length,

and thickness.

Tank Shell (Barrel) • To achieve the desired diameter,

the plate length must be pi

(3.1415) * diameter. For D=10’,

the plate must be slightly longer

than 31.14’.

• Once the plate is formed into a

cylindrical shape, the resultant

ring is moved to a location

where the two ends can be

welded together.

Tank Shell (Barrel)

• This picture depicts

the placement of a

second ring adjacent to

the first ring for fit-up

and welding.

• The fit-up is extremely

important to assure a

good weld joint.

These two rings are

not yet aligned.

Welding

• Joints can be

– Butt Welded

– Lap Joint Welded

– Joggle Joint Welded

– Other

• Welding made via

– Submerged Arc

– Flux Core Arc Weld

– Gas Metal Arc

– Shielded Metal Arc

Attaching the Heads

• After all rings have been

welded together,

bulkheads inserted, then

the final outside tank head

can be welded onto the

shell or barrel.

• Fit-up is an important

process in building a tank

to assure a good weld.

Production Tightness

Performance Test

• All atmospheric tanks are

tested with air pressure.

• Horizontal cylindrical tanks

are tested at 5 psi.

• Vertical tanks at 3 psi.

• Rectangular tanks are

tested at a pressure based

on its UL performance test,

normally 3 -5 psi.

Locating Pinholes

• All welds are further tested

during the pressure test

with a soapsuds solution.

• If the weld has a pinhole,

air will escape at the

pinhole and a bubble is

easily seen

• Welds must be repaired and

proven tight.

Adding Secondary Containment

• Most underground storage

tanks and many

aboveground storage tanks

are built with secondary

containment.

• Many of these tanks use

two walls of steel, although

underground tanks can be

built with a non-metallic

wall, also called a jacketed

tank.

Adding Secondary Containment

• After the primary tank

is built and tested, the

outer wall is fabricated

atop the primary tank.

• The second wall is

placed intimately atop

the primary tank wall.

• Such an intimate wrap

is called a Type I

containment.

Interstitial Monitoring Port

• Some fabricators will install a

pipe within the primary tank that

is used to monitor the interstice

for leaks.

• Others install the monitoring

pipe outside both tank walls.

• Both methods allow a liquid

sensor to be inserted into the low

point of the interstice for liquid

monitoring.

Preparing the Tank for Delivery

• After ancillary

equipment installed,

coatings applied, etc.

the tank is made ready

for shipment.

• Fabricators apply a

vacuum into the

interstice of secondary

containment tanks

Interstitial Vacuum

• After the vacuum is applied, the tank is held

in storage until it is made ready for delivery

• The vacuum remains on the tank during

storage, delivery, and during much of the

installation.

• An easy view of the vacuum gauge to verify

retention of the vacuum assures that both

walls remain tight.

STI Tank Registration

• Every tank built with

an STI labeled is

inspected by tank

fabricator to meet STI

specification

• Tank is “registered”

with STI

• STI maintains

database with over

400,000 entries

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

1988

1998

1971

2008

sti-P3 Tank

Installations

T

a

n

k

U

n

i

t

s

B

u

i

l

t

Years in Number after 1970

Tank Performance Evaluation

• All STI labeled UST’s

subject to 3rd party

warranty

• STICO Mutual has

strong claims

management program

• STI gets feedback on

quality and

performance

STI Quality Control Program

• Random inspections

performed by qualified

STI inspectors on

quarterly basis

• Mandatory attendance

at Quality Control

meeting

• Quality awards

Tank Compatibility - Biofuels

• E10, E15, E85, B2, B20, B100

• Steel Tank Manufacturer

Certification Statements

• STI Web Site

• Performance

• Tanks are Cleaner – Sludge

• Biodiesel Shelf Life

• Water Concerns

• Phase Separation - Ethanol

Recent Events

Biofuels

31

• Sumps

• EPA ORD Research

• NIST Research

• Publications

• “Compatibility of UST

Systems with Biofuels,”

• Published by ASTSWMO

• Case Studies

• Research and Work Groups

• Underground tanks storing

E85

Ultra Low Sulfur Diesel Issues

32

• Corrosion of metal components within steel and FRP tanks storing ULSD

• Clean Diesel Fuel Alliance supported research from Battelle Labs - completed in 2012

• Further studies under consideration

• STI Research

• Tanknology hired to visually examine the insides of steel and FRP ULSD tanks

• Fuel samples extracted and tested • Example – Las Vegas service station

tanks under same owner • FRP tank vapor control fitting –

top right photo • Steel tank vapor control fitting

– bottom right photo

Inspection and Maintenance

of the Tank System

Inspection and

Maintenance

STI R111

Storage Tank Maintenance STI SP001 AST Inspection

Perpetual Tank System Life

• Manufacturer’s Warranty

– 10 Year, 30 Year

• Steel Capabilities as a Material

• Desirable Operations

– Routine Maintenance

– Tank Inspection

– Fuel Usage

• Corrosion Protection

Component Life

1986 Sti-P3 E85 Tank

Removed in 2013 – No Leaks

STI/SPFA Water Industry Century Club

• Dothan, Alabama

• Dixie Tank

• Built in 1897

• City landmark

• Civic pride

• 116 years old

• Remains in operation

UL Tank Standards Update

A Reader’s Digest Summary of UL

Standards Work in Recent Time

UL STP 58

• STP = Standards Technical Panel

• STP 58 covers all UST standards

– UL 58

– UL 1746 and

– UL 1316

• In March 2012, UL called a meeting to start

the process of updating the UL standards

STP 58

• UL announced that scope of all standards

will remain as is – Flammable and

Combustible Products – until UL completes

their research on fuels.

• Task groups were formed to develop

proposals for both UL 58 and 1316

• Decided to start ballot process with 1746

because it had been a consensus standard.

UL 1746

• On Sept 21, 2012, UL posted comments for

preliminary review.

• This is the first step in the UL process to

update a standard.

• UL automatically posted for review all of

the older, outstanding items

• Other items were also requested for change,

totaling 17 topics for committee review

UL 1746

Agreement to move to ballot

• Of these 17 the committee agreed that 9 topics should move forward to the ballot process. – Update fuels to reflect modern fuels such as

biodiesel

– Add interstitial communication test

– Revise leak test

– Update glossary terms

– Update installation instructions

• In addition, proponents may move to ballot without preliminary consensus if they choose.

New – UL 1746

Update Fuels

• Addition of Biodiesel Blends

– Test fuel proposed is aggressive blend

– Includes water and acid in the test fuel

Modification – UL 1746

Interstitial Communication Test

• UL 1746 is the only UST standard to

require a communication test

• Purpose is to verify that interstitial space is

capable of communicating a leak

• Current test states tank must be buried

• Proposal is to allow additional options for

testing

Modification – UL 1746

Revise Production Leakage Test

• Proposal to add requirements to how tanks are

tested in the shop

• Standard currently allows both vacuum and air

pressure test

• Standard procedure nowadays for steel tanks is

to ship double wall tanks with vacuum on

interstice

• Proposal to make vacuum test more stringent

UL 58 and UL 1316

• After 1746 was issued for preliminary

review, work on 58 and 1316 came to a halt

– Time required

– Some prefer to see how issues resolved in 1746

• UL has no timeframe for reviewing these

standards.

Most Recent Editions

• UL 1316 last issued 1/4/1994 with technical

revisions dated April 2, 1996

• UL 58 last issued 12/13/1996 with technical

revisions dated July 27, 1998

• UL 1746 last issued January 17, 2007 as a

consensus document.

UL Voting Process

• Preliminary Review

• Balloting

• If consensus reached, but Negatives or Comments received, proposal submitter has to respond as follows: a) Accepting the Comment,

b) Rejecting the Comment,

c) Accepting the Comment in principle but with changes in the proposed wording,

d) Accepting the Comment in part,

e) Accepting the Comment in principle and in part,

f) Acknowledging the comment (when the commenter agrees with the proposal), or

g) Answering the comment (when the comment poses a question, but doesn’t advocate a particular technical revision).

• Then item is re-balloted

UL 142 – Steel ASTs

• Feb 3, 2012 UL issued bulletin starting the

process to revise UL 142

• 19 Proposals were issued

– Editorial items included in this number

• 15 items reached consensus

• Waiting to be published

• A few of the items that reached consensus

follow

Modification – UL 142

Vertical Tanks

• Proposal approved to change the language

back to how it read prior to 2007

– Add a limitation on tank capacity, 50,000

gallons

– Remove limitation on tank diameter

Deletion – UL 142

Markings

• Deletion of markings for tanks on supports

and diked tanks

– “On Supports”

– “Open Top”

– “Closed Top”

New – UL 142 Requirements for Minor Accessories

38B Minor Tank Accessories

38B.1 If provided, minor accessories intended for factory assembly or field installation to the tank shall comply with the requirements in 38B.2 and 38B.3.

38B.2 Mounting brackets for small equipment shall not exceed 4.0 ft2 (single side projected area), and shall be constructed of at least 0.093 inch thick steel. Mounting brackets greater than 4.0 sq ft2 shall comply with the Static Load Test in paragraph 36.3. The brackets and supporting structure shall be welded to the tank, or provided with bolted connections that are welded to the tank.

Clarification – UL 142

with Respect to Venting

8.4 A vent opening that provides for emergency venting shall have a capacity not less than that specified in Table 8.1. A vent opening that provides for both emergency and normal vents shall also have a total venting capacity not less than specified in Table 8.1, in addition to the requirements of paragraph 8.2.

Emergency vents are not prohibited from use for normal venting of the primary tanks if the tanks are marked as specified in 48.1.1(e).

New – UL 142

Requirement for Sumps

38.2 As an option, sumps no larger than 18 inches in with a maximum 24 inch diameter nor more than 6 inches in and maximum 12 inches depth shall be permitted in primary and/or secondary tanks along the bottom center line. The thickness of the sump material shall, at a minimum, be the same thickness of the tank shell or bottom, depending on the location of the sump and the type/orientation of the tank.

38.3 All internal welds are to be full seal welds.

38.4 Sump welds shall be a minimum 6 inches from a head or bulkhead weld.

Clarification- UL 142

Production Testing

• Some AHJ’s as well as tank purchasers are confused. The intent of UL 142 has been misinterpreted because some readers believe that all of the one time performance tests should be done as production tests on every tank.

– 45.1 Each primary and secondary containment tank, before painting, shall be tested by the manufacturer and determined to be tight against leakage using the method of the Tank Leakage Test, Section 39 described in paragraphs 39.1, 39.2, and 39.3.

www.steeltank.com

847-438-8265

wgeyer@steeltank.com

50,000 Gallon

Double Wall

ACT-100 Tanks

Installed at

O’Hare Airport