Frequently Asked Questions

What start-up spares are needed for the unheading valves?

• download-brochure-button 30 in Top Unheading Spares
• download-brochure-button 30 in Top Unheading Spares
• download-brochure-button 60 in Bottom Unheading Spares

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What is the typical steam consumption of the unheading valves?

• 60″ bottom valve: switch steam is 2000-6000 lbs/hr., normal up to 800 lbs/hr.
• 30-36″ top valve: switch steam is 300-720 lbs/hr., normal 100 -188 lbs/hr.
• Steam consumption will be dependent on the pressure delta between valve and drum, the recommended delta is 20-30 psi. Higher pressures simply result in greater steam consumption without further benefits to the valve.

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How quickly can unheading valves be unheaded and reheaded?

As the top and bottom unheading valves are fully automated and controlled by a remote operator, the coke drum can be unheaded and reheaded very quickly.

• The bottom unheading valve typically can be opened/closed within two to four minutes
• The top unheading valve typically can be opened/closed in less than one minute
• Stroking times may vary depending on HPU pressure and flow rate

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How long does it take from "order to ship" an unheading system?

Lead times (from production to delivery) vary with every project due to the differing complexities of the plants requests. The ‘typical’ project will generally take 48-52 weeks upon receipt of approved drawings and documentation.

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What is the life expectancy of the bottom unheading valve?

Life expectancy of the valves internal components are significantly impacted by the operating conditions within the coker unit. The general benchmarks are:

• Valve body and bonnets = 20 years
• Seats, rings, and gates = 5-7 years

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Does installation of your retractable center-feed device require additional deck space?

The center-feed device installs direction inline (above) the bottom unheading valve, so additional deck space in not required.  Modifications to the coke drum transition spool and feed lines are required to accommodate this installation.

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How long does it take to install an unheading valve?

Prior to your refinery’s turn-around DeltaValve’s engineers can come onsite to confer with managers, engineers, and other key staff to determine the best course of action for installing the new unheading valves. Depending on pre-installation preparation, most installations take between 2-4 weeks depending on valve quantities, engineering, and other refinery specific factors.

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What are the benefits of the retractable center-feed over traditional side-feed?

Side-feed entry (whether single or dual entry) tends to create flow channels favoring one side of the coke drum. These flow channels allow for rapid temperature changes directly against the coke drum wall causing significant thermal stress.  The center-feed device creates flow channeling up the center of the coke drum, allowing the resid to cool, building a consistent thermal layer building from the outside in, and in essence insulating the coke drum wall. Likewise, quench water follows the same internal to external flow channels and gradually cools the drum from the center outward. The center-feed process can significantly reduce coke drum thermal stress and extend coke drum life compared to side feed entry.

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How much do the unheading valves weigh?

• The bottom unheading valves weigh approximately 72,000 lbs., and is the lightest fully automated unheading valve in the world.
• The top unheading valves are significantly smaller and weigh approximately 12,000 lbs.

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Can we use our current cutting tool with your unheading valves?

DeltaValve’s unheading valves were originally developed with other cutting tools in mind. There have been no reported problems using current cutting systems with our valves. It wasn’t until after the top unheading was launched that the development of our own auto-switch cutting tool was developed.

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What are the space requirements for the bottom unheading valve?

Our bottom unheading valve is the smallest fully automated unheading valve available worldwide and will fit in most retrofit installations. The overall dimensions of the bottom unheading valve are ~20’L x 8’W x 3’H. Please contact your DeltaValve sales representative to review any space constraints or concerns you may have regarding unheading valve installations.

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Will the coke drum need to be modified to accommodate unheading valve installation?

Yes, the coke drum will need to be modified. The drum will need to be cut at near the bottom flange and replaced with a weld-in style transition spool. The transition spool will then connect to the bottom unheading valve with a bolted flange connection.

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