INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

If you want to learn more, please visit our website valve test table.

Contact Us

FIRST NAME *

LAST NAME *

MESSAGE *

ADDITIONAL DETAILS

Thanks. We have received your request and will respond promptly.

Log In

Come Join Us!

Are you an Engineering professional? Join Eng-Tips Forums!

• Talk With Other Members
• Be Notified Of Responses To Your Posts
• Keyword Search
• One-Click Access To Your Favorite Forums
• Automated Signatures On Your Posts
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving. By joining you are opting in to receive.

Posting Guidelines

Students Click Here

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Eng-Tips Posting Policies

control valves and piping hydrotest

• Forum

• Search

• FAQs

• Links

• MVPs

Control Valves and Piping Hydrotest

elylrc

(Mechanical)

(OP)

In the past, we have hydrotested systems prior to installing control valves by using a short spool in place of the valve. I have a contractor insisting that this is unnecessary. The system is ANSI 600#, Class Location 3, per B31.8. The design pressure and the test pressure are specified. The valve is by Mokveld. Any advice will be appreciated.

RE: control valves and piping hydrotest

DLite30

(Mechanical)

Our company standard is to remove control valves prior to hydrotest. The definition of a control valve is open to some interpretation. In my opinion, it depends on the specific valve you're using. I would remove it if:

• It has internal noise trim or any ports that can be plugged by sand, grit, or welding slag.
• It is a globe valve type control valve with a rising stem.

Other instances may also require removal. Some in our company consider any valve with an automated pneumatic actuator a control valve, which I find ridiculous.

RE: control valves and piping hydrotest

elylrc

(Mechanical)

(OP)

Many thanks for the input. It reinforces my experience. By "control valve", I mean the traditional type with a sliding mechanism. I agree, it's not necessary to remove other types of valves not prone to jamming by particulate matter.

RE: control valves and piping hydrotest

sheiko

(Chemical)

I would also ask for advice from the valve vendor.

RE: control valves and piping hydrotest

vpl

(Nuclear)

I'll second sheiko's advice. If it's a new system and valve, you want to ensure you don't void the valve warranty. Ensure the contractor takes full responsibility in writing if you follow his advice.

RE: control valves and piping hydrotest

elylrc

(Mechanical)

(OP)

Thanks Patricia, that was the first thing we did. Unfortunately, the vendor wasn't helpful, which prompted my question in this forum. Industry standards seem to suggest replacing them with a spool during pressure testing, aligning with my experience.

RE: control valves and piping hydrotest

sheiko

(Chemical)

The vendor wasn't any help? What do you mean?

RE: control valves and piping hydrotest

vzeos

(Mechanical)

Hydro tests are required by code to strength test line pipe. Components and fittings are usually exempt if they meet code requirements. Below is the section of CFR 192:

• § 192.505 Strength test requirements for steel pipeline to operate at a hoop stress of 30 percent or more of SMYS.
• ... (see original text for full code requirements) ...

RE: control valves and piping hydrotest

elylrc

(Mechanical)

(OP)

Thanks Vzeos. This plant is built to B31.8 standards. All valves, flanges, and fittings are normally hydrotested together to 1.4 times MAOP. However, control valves are not covered by API 6D, so we install a dummy spool before FGT operations and install the control valve later with a witch's hat.

RE: control valves and piping hydrotest

Duwe6

(Industrial)

Assuming no vendor warranty, hydro with the valves in. The tradition and term 'spool' come from instances where the last thing to arrive at a plant being built was the control valves. Short pieces with a flange on each end look like an oversized thread spool. The only problem, other than warranty, will be packing leaks. Bring the test pressure up to operating, adjust the packing to be leak-tight, and avoid over-tightening. Identified leaks of this nature are acceptable in a Code hydro, even at nuclear plants.

RE: control valves and piping hydrotest

elylrc

(Mechanical)

(OP)

Thanks Duwe6. We are going with the spool piece as it's not practical to gauge a pipeline with a control valve installed.

RE: control valves and piping hydrotest

BigInch

(Petroleum)

And, if you ever test with a valve "in", at least make sure it's open.

RE: control valves and piping hydrotest

BigInch

(Petroleum)

Leaving a control valve in for hydro is like driving crash test dummies around in a Ferrari.

RE: control valves and piping hydrotest

Kiwi

(Structural)

elylrc, just finishing a hydrostatic test procedure for piping on the $50 billion Gorgon LNG Project in Australia. The client is Chevron. Here are the specifications:

• Tests through control valves are permitted if no internal cage assembly or potential for damage exists. Tag those not suitable for testing and remove them.
• Pressure-balanced type control valves and their pressure connecting leads shall be isolated from the test pressure. Bypass and block them off with the drain or vent open and the pressure connection to the diaphragm closed or disconnected.

RE: control valves and piping hydrotest

ione

(Mechanical)

From Lees' Loss Prevention in the Process Industries Hazard Identification, Assessment, and Control - "Pre-test preparation: Remove or spade off any control valve or instrument liable to damage under test pressure."

RE: control valves and piping hydrotest

sheiko

(Chemical)

I agree with ione. Moreover, is it possible that the valve has already been hydrotested in the factory?

RE: control valves and piping hydrotest

elylrc

(Mechanical)

(OP)

Thanks all. The pipeline system was successfully flooded, gauged, and hydrotested. The control valves were reinstalled this morning.

RE: control valves and piping hydrotest

BigInch

(Petroleum)

Kiwi, that's the same as basically just telling you not to do it.

RE: control valves and piping hydrotest

davefitz

(Mechanical)

The valve design code's maximum allowable overpressure is 10% above design pressure, while most hydro tests are 30-50% above design pressure. If the 110% design pressure of the valve is exceeded during the hydrotest and it fails, then you own the valve.

RE: control valves and piping hydrotest

elylrc

(Mechanical)

(OP)

Dave, you may be confusing design pressure with test pressure. The B31 series allows 10% over design to account for transients. Remember, the hoop stress for design purposes is governed by the class locations and 80% SMYS is the limit for gas. However, during hydrotesting, as long as the steel doesn't yield, it's okay up to 100% SMYS. The non-steel internals are what you need to be careful with, like seals. This is why valves are tested in the half-open position.

RE: control valves and piping hydrotest

davefitz

(Mechanical)

elylrc, you may be undertaking some wishful thinking. ANSI B16.34 makes it explicit that any pressure test occurring above its 100 F pressure rating or differential pressure rating is solely at the risk of the user. So zero overpressure is permitted based on a 100 F rating. It's an issue for valves that normally operate at 100 F. If a valve fails during a hydrotest, the vendor will likely take refuge in the B16.34 statements.

RE: control valves and piping hydrotest

elylrc

(Mechanical)

(OP)

Pipeline valves are per API 6D per B31.8. I'm sure you may be correct in other applications.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts. The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login

News

An Overview of Valve Inspection and Testing

An Overview of Valve Inspection and Testing

Media flow hydraulic processes and procedures heavily depend upon quality valves. Failure in a piping system from faulty valves can incur considerable and costly damage. In some cases, these failures may risk catastrophic property damage or injury and death to workers.

Because of the critical role valves have in complex and intricate processes, proper inspecting and routine testing should be part of a risk mitigation plan. Today, we’ll go over the kinds of valves, industry standards, and testing you might encounter.

What is a Valve?

While the function of a valve is relatively simple, the designs are diverse and sometimes complex. Below is a list of valves you may already be familiar with, along with their applications.

• Butterfly Valve — A quarter-turn valve used to control the flow of liquid, gas, or particulate matter. It is used in treatment plants, food industry, ship industry, petrochemical plants, fire extinguisher systems, paper manufacturing, and many more applications.
• Ball Valve — A shutoff valve with a rotary ball that controls flow and pressure control in gas distribution systems, as well as pressure reduction in connection with gas storage. It is used in applications involving corrosive fluids, slurries, or normal liquid and gases. Applications are found in the oil and natural gas industry, manufacturing sectors, chemical storage, some residential uses, etc.
• Globe Valve — A linear motion valve used to start, stop, and regulate flow. It may be used for isolation and throttling. Applications include cooling water systems, fuel oil systems, feedwater or chemical feed systems, turbine lube oil, boiler, and main steam vents or drains.
• Check Valve — A one-way, non-return valve where the flow runs freely in a single direction and works to prevent backflow. It is used in pumps, fluid systems (for chemical and power plants), and more.
• Needle Valve — A plunger valve with a small opening (or port) that has a needle-shaped plunger allowing precise regulation of flow. It's ideal for systems with lighter and less viscous media with low flow rates or systems with small channels and pipes. This valve regulates gas or water through an appliance or system.
• Gate Valve — A sluice valve that is multi-turn and works by inserting a rectangular gate or wedge in the path of a flowing media. A threaded stem connects the actuator (such as a handwheel or motor) to the gate's stem. It is found in industrial applications such as pharmaceuticals, manufacturing, automotive, oil and gas industry, or marine. It's also useful in underground applications and is ideal for vertically-oriented setups (as it is space-saving).
• Pinch Valve — A full bore or fully ported valve that ‘pinches’ to obstruct the flow of fluids. It's used for liquid, solid, and slurry applications. It's ideal for isolating or regulating media that is abrasive, corrosive, and fibrous.
• Plug Valve — A quarter-turn rotary motion valve where a tapered or cylindrical plug is used to start and stop the flow of media. Applications include natural gas piping systems, oil piping systems, coal slurries, mineral ores, mud, sewage, or vacuum to high-pressure applications.
• Pressure Relief Valve — A safety relief valve designed to open at a preset pressure level and discharge fluid until an acceptable level of pressure is reached. It is necessary for applications where pressure levels are critical (such as oil and gas, petrochemical, or power generation using steam, air, gas, or liquid). Applications include firefighting, high-rise building systems, water towers or tanks, drinking water systems, or multi-phase applications in refinery and chemical processing systems.

Why is Valve Testing Important?

Smooth and safe operations of industrial processes and equipment rely on control valves that perform with precision. The quality of production is optimal