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ChE Plus Newsletter Volume 4, Issue 1

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Dateline: February 1, 2006

In this issue...
Article Contest
vol4iss1_3.gif (6701 bytes)The 2006 Article Contest is Here!
Top Prize is $350 USD
Think you can write a great article that our visitors would like to read?  Read more about the contest and learn how to enter here.
New Articles Available

The More You Know: Process Safety Information (PSI)
From our guest author, Mike McCue, read about what's important when conducting a Process Hazard Analysis.  Read the full article.

Flow Through Orifice Plates in Compressible Fluid Services at High Pressure Drops
The calculation of compressible flow through orifice plates at high dP (critical flow) appears to be carried out incorrectly in most instances. This flow condition is often encountered on gas plants....Read the full article.

Explosion in a Salt Bath of a Synthetic Fiber Plant
Synthetic fiber plants like Nylon and Polyester use a salt bath consisting of a mixture of sodium nitrate and sodium nitrite for cleaning metering pumps, spinnerette  assemblies, valves, and fittings coming in contact with polymer melts....Read the full article.

Factor Affecting the Quality of Quicklime
To conserve natural resources and comply with responsible care initiatives, the soda ash industry has concentrated on optimal and effective utilization of lime in the ammonia recovery section of the soda ash process....Read the full article.

Samudra Manthan - Mining the World's Oceans
Salt affects our lives and our needs more than anything else.  In industry, salts are important raw materials for heavy chemical industries that require high quantities of salt with fewer impurities, like calcium magnesium.... Read the full article.

Pyrophoric Iron Fires - UPDATED
Read the lesson submitted by one of our visitors in this quick update to a popular article on our site.  Read the update here.

New Software Titles Released
excel_icon.gif (986 bytes)Pressure Venting of Dust Explosions (VDI Edition)
Calculate the pressure venting requirements for dust explosions based on VDI 3673, Part 1, November 2002. This a German technical document which is used to govern such requirements in many areas outside of the U.S.

excel_icon.gif (986 bytes)Flammable Mixtures - Flash/LFL/UFL
Two calculations are included with this title:
1. Estimate the flash point of a flammable and inert material via Raoult's Law.
2. Determine Lower and Upper Flammability Limits of a flammable mixture via Le Chatellier's Law.

excel_icon.gif (986 bytes)Ezze Triz
EZZE TRIZ is essentially ‘cook book’ problem solving with a recipe, which follows the procedures discovered by Altshuller to find an innovative solution to a particular problem.

Vent Requirements for Steam Cleaning Vessels

Over the years, we've seen far too many innocent vessels fall victim to a lack of sufficient venting when steam cleaning was being performed.  Are you sure that your vessels have the appropriate amount of venting capacity?  Condensing steam can create a powerful vacuum that can damage your vessel beyond repair.  Before steam cleaning your vessels again, check your venting requirements with our easy to use software tool entitled "Various Relieving Scenario Calculations".  This spreadsheet includes the following relieving scenarios:

  • Steam condensing on tank surfaces

  • Cold water spray - steam condensing

  • Vacuum hazards from drainout and pumpout

  • Tank venting for gas and liquid inflows

A truly flexible software title and it can help in many circumstances.  There's also a preview available here.

Overheard in the Online Forum

Safety Valve Capacity

"We have safety valves on a initiator feed vessel which are blanketed with nitrogen.  They are designed for a fire case, control valve failure, and overfilling.

The initiators are peroxides solutions with heptane and they are susceptible to decomposition.  The valve flow rate is 18000 kg for the fire case, 780 kg for nitrogen failure and much less for overfilling.  The set pressure for the valve is 5 bar.

This means that a pressure relief valve can also act as a thermal relief valve which in the case here is overfilling.

What does the fire flow rate mean?  Does it mean that the valve, when fully open, must be capable of relieving 18000 kg/hr in the event of a fire outside the vessel and heat from the fire increasing the pressure in the vessel?"

Read the replies to this message

Website Spotlight

vol3iss1_spreadsheet.gif (5149 bytes)Looking for another great engineering website?   Checkout  Consulting engineer Paul Ostand has provided many great articles on tank blanketing techniques.

Also, check out to learn more about optimizing your recipe blending procedures.

Launch of Enterprise Asset Management Section
Mr. Mike Sondalini joins us as a guest author in his new column entitled "Enterprise Asset Management".  Read his latest column "What is the Purpose of Equipment Maintenance?"
Software Spotlight

vol4iss1_1.gif (5570 bytes)Bolt Torque Calculator

Calculate the torque required to tighten UN inch size bolts such as piping flange bolts to a required level of tension without breaking them. See how much or how little of the torque actually goes into achieving tension in the bolt. See the Mohrs Circle and Ductile Failure Envelope conditions both during tightening and after installation. See the effect of various lubricants and bolt surface finishes. Set up to work with UNC, UN8 and UNF inch size bolts to ASTM A193 and A320 bolt materials but with the ability to deal with other thread types and materials. All of the formulas used are provided in the worksheet and the calculation is presented in both US and SI units.
  The interface is extremely user-friendly and can be previewed here.

When you're ready to get your copy of the Bolt Torque Calculator, you can purchase from the online store and download the software immediately.

CE Credit Discounts
Did you know that you can get a 10% discount on a variety of online CE courses offered by  Visit the CE Credit section of our online store for instructions.   Remember, don't put the course in your "basket", use the link provided with each course description to order from
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