Dished Ends FAQs

Dished Ends FAQs

March 26, 2019 apvheads 0

Australian Pressure Vessel Heads is Australia’s leading manufacturer of dished ends, pipe caps, pressure vessel heads and tank heads for use in the fabrication of pressure vessels, storage tanks and process vessels. Our valued customers include large and small companies in the petrochemical, chemical, power, water treatment, food and offshore industries.

Australian Pressure Vessel Heads manufacturers dished ends of up to 10 meters in diameter, with material thickness ranging from 5mm to 125mm, and has the capability to manufacture larger segmented configurations.

With more than 60 years’ experience and products of the highest quality, we are able to provide our customers with complete peace of mind.

This is an informative guide to help buyers of dished ends ensure they ask they right questions before making a decision on what dished ends manufacturer to select.

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How Do I Order a Dished End?

It is important to know the following specifications when ordering your Dished ends

  1. Quantity  
  2. Material type or grade
  3. The manufacturer code
  4. Shape
  5. Inside and outside diameter
  6. Inside radius (for torispherical type)
  7. Straight flange (for torispherical type)
  8. The minimum thickness after forming (for torispherical type)
  9. ITH (tarsus article)

 

What are the common causes of Dished End failures?

  1. Microscopic cracks –  a common issue in cold pressed dished ends where it could suffer excessive thinning in the process (cold forming). This rarely happens when using the hot pressed method.  Based on record, there is a 10% maximum thinning and this only happened 5% of the cases based on Australian Pressure Vessel Head’s record.
  2. Incorrect welding procedure
  3. Design

 

 

How important Is the appearance of a Dished End?

The appearance does not determine the quality of the Dished Ends. In fact a hot pressed dished end usually products a rougher finish but better quality dished end, while cold forming is the opposite.

The more common cold pressed dish ends generally appear shinier because of its finish.  While hot pressed types, which are a lot superior than cold pressed, can be prettied up with a shot blasting and prime coat painting finishing touch.

 

How would you know the quality of the Dished End by looking at it?

When performing a visual inspection, it is highly important to look for the following signs to make sure that you are getting a product of superior quality:

  1. Crown radius – make sure the dished end was deep enough.  Check the corner radius, or the knuckle radius, and make sure that radius was not too small.  It would have to be at least 10 or 15%, if it’s a true rate [0:31.3]
  2. Weld seam – it has to be either radiographed or ultrasonically examined to check for cracks in the weld, or the weld affected zone.  
  3. Irregularities in shape
  4. Irregularities in size
  5. Code requirement numbers/digits

 

What are the consequences of buying a poor-quality Dished End?

  1. Poor quality dished ends may not fit the barrel that has been rolled for that particular job
  2. It may have cracks built into it that nobody can see, and they won’t become obvious until the vessel is in service.
  3. Explosion from dished end failure which could result result in injury or worse, death.  

 

What are the various shapes of Dished Ends?

  1. Torispherical –  The shallowest of the three main dished ends – this type has less dishing and so it is cheaper to produce
  2. Simulated sorter – has a bit deeper dishing There’s more drawing time.  The blank size is bigger. So, there’s a higher material cost, and a higher forming cost.  And, it can withstand a higher pressure than the Torispherical for the same diameter and thickness.
  3. Hemispherical –  Can withstand a higher pressure.  It is deeper, and the blank is bigger. This the the most efficient among the three types, but is the dearest to make.  

 

What criteria would you use to find the best supplier of Dished Ends?

One should look for a supplier with a past record.  A good track record. Australian Pressure Vessel Heads has been in the business supplying top quality Dished Ends for around 70 years.  It has supplied Dished Ends to all of the refineries in Australia, none of our Dished Ends or pressure vessels have ever failed to this day.  

 

What makes a great Dished End?

A great Dished End is formed strictly following specific codes and all Australian Pressure Vessel Heads Dished Ends strictly conform to these requirements.  Customers are assured they get the right size and shape for their requirement.

How to choose what material to use in making your Dished End.  

There are different types of products that are used to create Dished Ends

  1. Standard boiler plate – it is the most common steel used with various material types depending on function:
    • PT460NR for designing vessels
    • PT490NR (slightly thinner than PT460NR)
    • ASTM A316 or ASTMA304  for corrosive environments
  2. Chromium molybdenum steel.  
  3. Nickel-based steel.

 

What types of things can Dished Ends be used for?

Dished Ends can be used for a variety of products. Some of the products that we have produced dished ends for includes:

  1. Seal off the ends of a pressure vessel, and, or a storage tank – the most common use   
  2. For council arts and outdoor art installations.  
  3. Oil sumps.  
  4. Bollards.  
  5. Pup plants
  6. Barriers
  7. Dive Tanks
  8. Hyperbaric Chambers.  
  9. Medical Equipment
  10. For Marine Equipment
  11. Oxygen tanks for divers

 

Famous Dished Ends

Academy award film director James Cameron who’s known for the film Titanic trusted Australian Pressure Vessel Heads to manufacture the casing of the pod of the vessel that set a world record for diving to the lowest point of the Earth in the mariana trench at a depth of 11 kilometres below the ocean’s surface. His life really was at risk with all of the intense pressures at that level so choosing the best quality material for the vessel was imperative.

Like any other loyal customer, James Cameron trusted that he could rely on the quality of the product that was being produced by Australian Pressure Vessel Heads.  Because they have been hot forming these Dished Ends for 70 years and have never had one fail yet.


The benefit of Australian Made

Buying Australian steels do not just guarantee its customers a quick turnaround,   they are also fully certified following strict Australian standards.

 

What’s the potential impact of material that’s a lower quality than expected in terms of costs and safety to the incline?

  • The pressure vessel could fail under service, which could result in an explosion, resulting in death or injury
  • The company that would sell a defective product,  would eventually suffer a significant reputational risk, a reputational damage.

As such when selecting a Dished End manufacturer, it is important to look at their track record and how long they have been in business for.

 

Get in Touch

For a quote on your Dished End requirement click on the button below

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To speak to one of our engineering experts, call us on +61 3 9311 7722

 

  AUSTRALIAN PRESSURE VESSEL HEADS

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