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Last updateMon, 29 Aug 2016 5pm

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Valve Basics Training Helps Fill Industry Skills Gap

Valve Basics Training Helps Fill Industry Skills Gap

One of the most keenly felt needs in tod...

An End-User’s Perspective on Valve Selection and Risk

An End-User’s Perspective on Valve Selection and Risk

I am not a valve expert, although I ofte...

New Test Stamp and More Updates on Pressure Vessel Codes

New Test Stamp and More Updates on Pressure Vessel Codes

A new test organization program and stam...

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Industry Headlines

Why Some Manufacturers Are Returning to the U.S.

Monday, 29 August 2016  |  Chris Guy

According to The Reshoring Initiative, “between 2009 and 2016 more than 250,000 jobs were created or brought to the U.S. from other countries,&r...

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Industry Headlines

ValvTechnologies Successfully Completes NUPIC Audit

5 DAYS AGO

ValvTechnologies, Inc. recently achieved NUPIC-approved suppliers list status, upon successful completion of the Nuclear Procurement Issues Committee (NUPIC) audit conducted at the Houston facility. NUPIC members include all domestic U.S. nuclear utilities as well as several international members.

Form...

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GE Oil & Gas Supporting ONGC’s Exploratory Drilling Campaign in India

5 DAYS AGO

GE Oil & Gas has been awarded a multi-million-dollar frame agreement by Oil and Natural Gas Corporation Limited (ONGC), India’s largest exploration and production company. Under the agreement , GE will provide an estimated 55 subsea wellheads (SG5) over next three years for the operator&rsqu...

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Oil Refiners Face Reprieve as Maintenance Tames Fuel Glut

9 HOURS AGO

“Oil refiners reeling from tumbling profits can expect some reprieve in the coming weeks as lower production could tame a huge global excess of gasoline and diesel,” Reuters reports .

“Dozens of plants that will switch off for regular autumn maintenance will help slow the downward spir...

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Chemical Activity Barometer Suggests Accelerated Business Activity

6 DAYS AGO

The Chemical Activity Barometer (CAB) expanded 0.4% in August following an upward revision for July. This marks the barometer’s sixth consecutive monthly gain. Accounting for adjustments, the CAB is up 3.2% over this time last year, the strongest year over year growth since January 2015. All d...

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Why Some Manufacturers Are Returning to the U.S.

9 HOURS AGO

According to The Reshoring Initiative, “between 2009 and 2016 more than 250,000 jobs were created or brought to the U.S. from other countries,” PBS NewsHour reports .

“A number of factors have influenced the creation of jobs in the U.S., including rising labor costs overseas, higher fr...

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Manufacturing Productivity in U.S. Higher Than Other Nations

4 DAYS AGO

“U.S. productivity unexpectedly declined for a third straight quarter in the three months through June, Labor Department figures showed. On a year-over-year basis, it fell for the first time since 2013,” Bloomberg reports .

But on a more positive note, “the U.S. still blows other natio...

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Safety-Relief Valve FAQ

Our company routinely receives inquiries from end users about their safety-relief valves.

Here are some of the most frequently asked questions...


Q:  What is the proper way to install a safety or safety-relief valve?

A: Safety and safety-relief valves should be installed vertically with the drain holes open or piped to a convenient location. All piping must be fully supported.

 

Q:  How often should I test/ inspect my valve?

A: Maintenance should be performed on a regular basis. An initial inspection interval of no longer than 12 months is recommended. The user must establish an appropriate inspection interval depending on the service conditions, the condition of the valve and the level of performance desired.

The ASME Boiler and Pressure Vessel Code does not require nor address testing installed valves. The only thing the code states are design and installation requirements, such as some valves must have a lifting lever. For instance for Section VIII:

“Each pressure relief valve on air, water over 140° F, or steam service shall have a substantial lifting device which when activated will release the seating force on the disk when the pressure relief valve is subjected to a pressure of at least 75% of the set pressure of the valve.”

Q: What mounting orientation should be used to install a safety valve?

A: Installing a safety valve in any position other than with the spindle vertical and upright may adversely affect performance and lifetime.

Q:  Why is there a hole in the valve body?

A: This drain hole is required on some models by the ASME Boiler and Pressure Vessel Code. It is intended to prevent any condensate from accumulating in the body that may freeze or corrode internal valve parts and prevent the valve from opening. The drain hole should be piped away to safely dispose of any discharge or condensate.

Q: Which end should be connected for vacuum valves?

A: This is often a confusing topic. The correct installation often looks backwards from what appears to be correct. A paper instruction tag illustrating the proper connection is attached to each valve. Vacuum valves should have the NPT threads that are cast integral to the body attached to the vacuum source. See the assembly drawing for additional clarification.

Q:  What set pressure should the valve be set to open?

A: Typically, the valve should be nameplate set to open at the MAWP (Maximum Allowable Working Pressure) of the vessel the valve is intended to protect. There is a tolerance to actual set pressure, which means a valve set at 100 psig nameplate may open slightly above or below 100 psig. Consult the current ASME Boiler and Pressure Vessel Code for tolerance classes and special situations when the set pressure may be different than the MAWP.

Q:  Why is my valve leaking?

A: It is normal for spring-operated safety valves to exhibit leakage or simmer/warn, as the system operating pressure approaches the nameplate set pressure, typically in the 80%-90% range of nameplate set pressure. The ASME Boiler and Pressure Vessel Code does not require a specific seat tightness requirement. A certain level of leakage is allowed per manufacturers’ literature and API-527 Seat Tightness Performance Standards, both of which can be found in the Technical Reference Catalog and in the Data Supplement, summarized as follows:

  • Factory Standard Seat Tightness Performance: No visible (no audible for air service) leakage for 15 seconds (30 seconds for liquid or Section IV steam service) at 20% below nameplate set, or 5 psig below nameplate set, whichever is greater. EXCEPTION: Section IV steam service is checked at 12 psig.
  • API-527 Standard Seat Tightness Performance: A Functional Test Report (FTR) is automatically provided for valves ordered to API-527. See API 527 for complete details.

At very low set pressures, the ratio of the downward spring force as compared to the upward pressure force is very small. In these cases it may be impossible to achieve seat tightness.

Use soft seats for superior seat tightness, assuming the application falls within the soft seat temperature limitations. Although soft seats will typically provide a higher degree of seat tightness than metal seats, Factory Standard does not ensure bubble-tight seats, regardless of seat material.

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