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PADEP Aboveground Storage Tank (AST) Inspections

TECHKNOWSERV CORP. is a Pennsylvania Department of Environmental Protection (PADEP) Storage Tank Certified Company.   TKS is an industry leader in in above ground storage tank testing using Acoustic Emission (AE) technology, Ultrasonic (UT) straight beam and shear wave, and other conventional NDT methods such as Visual Testing (VT) – including Remote Visual Inspection (RVI), Magnetic Flux Leakage (MFL), Magnetic Particle Testing (MT), Penetrant Testing (PT), and Vacuum Box Examination (VB).  TKS has an American Society for Nondestructive Testing (ASNT) Level III Certification holder that is also qualified by the Pennsylvania Department of Environmental Protection (PADEP) to inspect both Aboveground Manufactured (IAM) and Aboveground Field Constructed (IAF) storage tank systems and facilities.  The ASNT Level III technician also maintains an American Petroleum Institute (API) 653 Certification, thus developing a compliance for all state and federal regulations in Pennsylvania.

For the past 15 years, TKS has provided quality above ground storage tank testing services both nationally and internationally.  Combining TKS’s experience with the PADEP storage tank inspection certifications has presented TKS, and Pennsylvania above ground storage tank owners, with a unique opportunity.  TKS offers annual above ground storage tank inspections with an online database that can be accessed 24/7 to acquire all relevant documents relating to any tank.  TKS has performed inspections on various sizes of tanks including tanks of 500,000-gallon and even 1,000,000-gallon+ capacity.  Above ground storage tank owners can be assured that any of the IAM or IAF AST inspections performed will be carried out at the highest level and meet every standard set by the PADEP.

TKS maintains API-653 above ground storage tank inspectors and non-destructive testing technicians on-staff to perform the above ground storage tank field inspection, data analysis, and technical reporting.   In Pennsylvania, an above ground storage tank is defined by the PADEP as a system consisting of tank or combination of tanks and the piping and ancillary equipment attached to it.  An above ground storage tank must be at least 250 gallons with 10 percent or less of the volume underground.

 

PADEP Aboveground Storage Tank Size Classification


PADEP aboveground storage tanks are further also categorized as large and small tanks.  

  • Large AST: any AST with a capacity greater than 21,000 gallons.
  • Small AST: any AST with a capacity less than or equal to 21,000 gallons

 

Additionally, vaulted ASTs are regulated under the large AST section regardless of size.  

 

An PADEP aboveground storage tank inspector is required meet the following standards of performance:

 

  • Maintain current technical specifications, manuals, codes and standards.
  • Submit complete, accurate, and timely reports of inspections and tank handling activities.
  • Maintain records of activities for 10 years.
  • Report releases and suspected contamination to the Department in writing within 48 hours of observation.

 

 

PADEP Aboveground Storage Tank Inspection Intervals 

The inspection interval for aboveground storage tanks differs for large ASTs (>21,000 gallons), small ASTs and vaulted tanks.   The following table summarizes the different inspection frequencies.

 

Large AST:

  • Out-of-Service: Every 20 years
  • In-Service: Every 5 years

 

Small AST:

  • Out-of-Service: N/A
  • In-Service: Every 5years

 

Vaulted Tanks: 

  • 6-12 months after installation, then every 3years 

 

Tank Linings must be inspected every 10 years.  In some cases, tank lining inspections may be extended if the tank liner manufacturer attests to the lifetime of the liner material for the specific product stored.  

 

 

PADEP Aboveground Storage Tank Inspection Form 

The inspection form is a 5-page form that that requires up to 17 different sections to be completed depending on the tank inspection circumstances and specifications.  The first sections are largely administrative and specify inspection type, dates, facility information, inspector information, tank identification, and fire/safety permitting.  The type of inspection, either in-service or out-of-service, must be selected.  Important inspection dates including inspection completion date, last out-of-service inspection, last in-service inspection, and last lining inspection must be recorded.  It is also required to document DEP Tank ID number, Owner’s Tank ID number, nominal capacity in gallons, tank diameter, tank height, substance stored, original construction code, and installation date.

 

A critical part is the Evaluation of Tank System section.  In this section the following specific items are assessed and reported on; Materials meet specifications/ compatible with substance, Foundation and tank supports, Tank shell, Tank roof, Tank bottom/floor, Internal linings & coatings, if installed, Tank Labeling, External deterioration protection, Appurtenances, Ancillary equipment (including piping) and 

Cathodic protection system.  For each item the PADEP aboveground storage tank inspector must select Satisfactory, Unsatisfactory,  Unsatisfactory Cannot Return to Service, or Not Applicable.

 

There is also a section dedicated to tank shell and tank floor corrosion rates and next in-service, out-of-service, and tank liner inspections.   The corrosion rates are calculated by using the historical tank and floor wall thicknesses.  For example, if a tank shell was 0.500 inches in 2013 as determined by ultrasonic thickness testing and was measured to be 0.450 inches in 2018, the corrosion rate is 0.01 inches/year.  Using the corrosion rate and minimum allowable tank shell or tank floor thickness, the next tank inspection date is established. 

 

Tank Record Review

The tank owner must maintain the minimum required documentation on-site and make this available to the PADEP tank inspector for review.  This includes the written operations and maintenance plan, spill prevention response plan, monthly inspection records available for the past twelve months, 72-hour inspection records available for the past twelve months and whether a leak test was required at the time of this inspection. 

 

Tank Information

Additional basic information about the above ground storage tank is required.  The PADEP aboveground storage tank inspector must specify tank construction; Single wall steel, Double wall steel, Single wall fiberglass, Double wall fiberglass, etc.   The piping used must also be specified and may include steel, fiberglass, PVC, stainless steel, etc.  Additional information like overfill protection, tank cathodic protection, and emergency containment is also required. 

 

Aboveground Storage Tank Cathodic Protection

The cathodic protection used must also be specified is categorized and None, Impressed Current, or Galvanic.    

 

If None is selected, the inspector must specify if the 

  • Tank is non-metallic 
  • Tank bottom is not in contact with soil or electrolyte 
  • Corrosion engineer determined tank bottom does not require Cathodic Protection. 

 

If Impressed Current is selected, the inspector must specify if the 

  • Tank Bottom was evaluated by a corrosion engineer
  • Engineer’s specifications are available. 
  • Rectifier is on and functioning within engineer’s specifications. 

 

If Galvanic is selected, the inspector must specify if the 

  • Tank Bottom evaluated by a corrosion engineer. 

 

Additional sections are required to be filled on the PADEP Aboveground Storage Tank Inspection Summary form with some of the critical section identified and explained in this article.   The PADEP aboveground storage tank inspection guidelines and forms are accessible on the PADEP aboveground storage tank website.

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