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ZEN Industries eNewsletter:
March 2022

Van Stone Flanges

At ZEN Industries, we recently fabricated another order with Van Stone flange joints.

Van Stone Flange from ZEN IndustriesWhat is a Van Stone Flange?

What benefits does a Van Stone flange bring to the table, compared to other standards like welded neck flanges, slip on flanges, and threaded flanges?

Van Stone refers to a two-piece flange with a rotating ring. It’s a type of lap joint flange where the bolt ring on the flange rotates separately from the hub, making bolt alignment easy during installation.

Van Stone flanges are used to join lengths of piping and valves and can be used to join HVAC spiral duct as well.

The Van Stone system is sometimes also referred to as a “Conrac” flange. The Conrac Corporation of California originally developed the Van Stone system as a way to make the manufacturing of pipework more labor and cost efficient, as well as providing a superior technical joint.

According to SMACNA, the major advantage of the Van Stone connection is labor savings. First, it eliminates the need for welding. Second, because the backing flanges rotate for alignment, manhandling of piping to achieve a good fit is also eliminated. Van Stone flanges can be fitted to piping and ductwork during fabrication, offering industrial precision and cost savings, or in the field when necessary.

Van Stone Flanges from ZEN Industries

Benefits and Limitations of Van Stone Flanges


  • Labor savings during installation.
  • Connections line up perfectly, and welding can be eliminated (depending upon static pressure requirements).
  • Disassembly for inspection is easy and practical.
  • Save costs by using different materials for flange parts that interact with piped substances and parts that do not (i.e. the backing flange and stub end).


  • While superior to slip on flanges, Van Stone flanges (non-welded) are not designed for high pressure applications.
  • When selecting gaskets and sealants for airtight joints, operating temperature and piped materials must be carefully considered.
  • The clamping pressure produced by the connecting bolts may not prevent distortion or leakage in large diameter ducts under negative pressure or large loads.

Van Stone flanges are an excellent option for safe, reliable joints with optimal cost-effectiveness. How do you know if they are right for your specific project or application? Call ZEN Industries today at 877-600-0274, or visit our Contact Us page.

Efficient Estimating

HVAC Estimating at ZEN IndustriesChoosing a Van Stone flange system is about using the right technology to achieve the best results at the lowest cost. At ZEN Industries, we’ve been pioneers of cost savings, efficiency, and high-quality services for the HVAC industry since 1999.

Another area where we excel for our customers in in our estimating department—ZEN M.E.P. Over the years, we’ve consistently seen HVAC projects and contractors fall behind and be seen as less competitive due to inaccuracies and duplication in their estimating process.

Between the efforts of the General Contractor, HVAC Contractor, and HVAC Fabricator to win any given job, the estimating process is often duplicated at least once. Adding to the potential for error is double data entry, which often occurs as data is entered manually into estimating, accounting, and production systems separately.

The more accurate the estimates, the less time wasted in process duplication, and when double data entry errors are eliminated, the difference is thousands to tens of thousands of dollars saved on a project. This is because accuracy at the beginning, starting with the estimating process, flows through to create labor saving at the job site too.

Partnering with Mechanical Contractors

Estimator at Work, ZEN IndustriesFor select mechanical contractors, ZEN M.E.P. partners in a way to help you bid on more jobs, in less time, and with greater accuracy. By eliminating the extra estimating that used to be necessary, costs are lowered and more bids are won.

As a partnering service, we work to integrate ZEN’s HVAC fabrication pricing with your company’s computer estimating software.

 Now, in one step, the mechanical contractor can generate a reliable quote as well as data that can be fed seamlessly into production, direct to your production line or ZEN’s own coil lines and plasma tables.
How do you qualify for ZEN’s partnering program?

Give us a call at 877-600-0274, or visit our ZEN M.E.P. Contact Page.

Smaller contractors can still benefit from ZEN’s experience and services. We offer time and material estimating and contracted estimating services as needed.

Partner with ZEN to Do More and Earn More

Let ZEN Industries be your partner in the HVAC Industry as an experienced, high-quality manufacturer of HVAC duct of all types. Our goal is to partner with our customers in ways that make the entire workflow from order to installation a seamless exercise in time and cost savings.

As an experienced fabricator of HVAC duct for over 22 years, ZEN Industries supplies traditional Rectangular Ductwork as well as Spiral Ductwork, Double Wall Spiral, , PCD Ductwork, and Industrial Welded Ductwork.

Success is All About Great Service

Founded in 1999 on a set of unbreakable core principles, ZEN strives to provide top-quality fabrication, advice, and planning for our customers.

The quality of our HVAC duct work is of the highest caliber and our price is competitive with the best in the industry. Of course, ZEN Industries Inc. gains its edge with unbeatable service, and service means people - it's about our experienced personnel and the relationships we build with each and every customer.

At ZEN Industries, we believe success is all about great service. Our affordable HVAC shop drawings, estimating services, and duct fabrication can be reached at 877-600-0274, or visit our Contact Us page today!

Learn more at www.ZENindustries.com

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