What are the Differences in Applications of Welding Neck Flange and Forged Blind Flange?

An Initial Introduction

The piping flange products in our industries mostly have a variety of designs, but two of the items are very frequently present on the procurement list, which is Welding Neck Flange and Forged Blind Flange. Both are forged items, follow similar set of international standards, and are manufactured from the same set of materials. The similarity of the materials leads to confusion to the extent that sometimes buyers even believe one product to be the substitute of the other. In fact, these flanges are designed to solve quite different engineering problems.

Why Do These Two Flanges Keep Coming up as Flange Types?

Industrial and process pipelines use both Welding Neck Flange and Forged Blind Flange in their applications to a great extent. As these two flanges are available in similar pressure rating and same material grades they come frequently together in a single project quotation.

Purchasing is the main cause of confusion here, not engineering. One might see two similar forged flanges of the same dimension and think the cheaper one is as good as the other. But the truth is that an experienced engineer does not just go by the looks rather tries to understand the role of the connection. He may then first check out what the pipeline connection is to achieve.

Should the pipeline carry fluid continuously under very rough environment conditions? The answer may be the Welding Neck Flange. However, when it becomes necessary to close up the end of a piping line temporarily or shut down some machinery for servicing in future then the Forged Blind Flange is clearly the way to go.

Welding Neck Flanges Perform Better Here?

Welding Neck Flanges are mostly preferred in piping systems which operate under pressure and temperature fluctuations. The long tapered hub of the flange helps to create a smooth transition from the pipe to the flange which in turn allows better distribution of stress over the connection area.

Because of these design features, Welding Neck Flanges are mainly found in refinery piping, offshore platforms, chemical processing, and high-pressure steam lines. These environments require that the flanges are highly resistant to fatigue and have very good sealing properties over time.

The other benefit of a Welding Neck Flange is the weld integrity. Since the flange is joined to the pipe through butt welding, the resulting connection is quite reliable with almost no risk of failure. Engineers often prefer to use a Welding Neck Flange when vibration, pressure cycling, or thermal expansion are potential issues affecting the long term reliability of the system.

Generally, Welding Neck Flanges may need more welding at installation compared to a couple of other flange designs, many operators believe that extra time is justified as it will minimize the possibility of maintenance issues while the pipeline is being used.

What’s the Value of Forged Blind Flange?

While the role of a Welding Neck Flange is to provide a continuous flow through the pipes, that of a Forged Blind Flange is to seal the end of a pipe. Instead of connecting two pieces of pipe, a Forged Blind Flange is mounted onto a pipe, pressure vessel, or equipment nozzle.

This very simple and limited use case makes the Forged Blind Flange, as they are also referred, a vital component in the majority of industrial setups. When doing pressure checks, blind flange are temporarily placed on some of the lines to create a safe working environment. Similarly, blind flanges can be added for maintenance reasons so that while one department is out of operation, others can go on with their production schedule.

On the other hand, many project managers hold certain pipe lines for their further connection to the system if they don’t have the equipment for them yet. A Forged Blind Flange is, so to speak, their solution till that time, which ensures future flexibility in the system while not interfering with present operations.

Decisions Based on Real-life Engineering Cases

When comparing these two products, engineers mainly look at the requirements of the connection and not at the price first.

Certainly, if the job is, let’s say, carrying fluid through the pipeline under pressure, the preferred option generally is a Welding Neck Flange since it after welding becomes actually one piece with the pipe. It enables an almost maintenance-free operation especially in applications that deal with, say, pressure surges, vibrations or constant thermal expansion.

A Forged Blind Flange, in contrast, is designed not for allowing passage of the process fluids but rather for making a tight closure at the end of the system. Hence, it is common for such flanges to be used as equipment nozzle closers, hydrostatic test flanges, spare branch connection flanges or even pipe closure flanges for future extension of the lines.

Therefore most projects these two products are not alternatives at all rather they are the same flange types which perform two completely different roles in piping systems.

Top Procurement Errors Made

A big misunderstanding is seeing every forged flange the same, so long as the pressure classes are equal. In reality, the design purpose is at least as important as the pressure level.

For example, there is no way that you can put a Blind Flange in place of Welding Neck Flange. A Welding Neck Flange provides a permanent pipeline flow whereas a Forged Blind Flange serves to totally seal the pipeline at the end.

Another common problem is choosing the item that looks the cheapest. In the end, the less priced part might result in more work with pipe fabricators or in the form of maintenance problem due to it not matching with the original design of the piping line.

Usually, experienced buyers look at operating pressure and temperature, pipeline design, planned maintenance, and relevant standards before deciding whether they need to use a Welding Neck Flange or a Forged Blind Flange.

The Benefits of a Manufacturer who has the Experience

Metal flanges are manufactured according to standards which detail specifications, but manufacturing quality directly affects how they perform on the job.

Each flange that Sunwen supplies is a Welding Neck Flange or a Forged Blind Flange that has been produced by an established factory with a system of checks in quality control to ensure consistency from the very beginning of each process.

We at Sunwen follow world standards such as ASME, ANSI, DIN, EN, JIS and GOST and provide a wide range of customized specifications according to project requirements.

In the pipeline sector, the quality of products is a top priority for Engineering Contractors, EPCs. and Distributors. It is the reason that besides price, we pay more attention to other important performance criteria like dimensional accuracy, sealing function, and ability to resist unexpected downtimes at the production stage.

Taking It All into Account

Finding differences between Welding Neck Flange and Forged Blind Flange does not mean to pick one because you think the other is good or bad, but rather because you know what they are built for. One is a long welded pipe piece of the system. The other is an end cap to prevent a pipe run or piece of equipment from operating.

A welding neck flange allows process continuity by making a strong, welded junction to the pipe, whereas for forging reasons, a blind flange ensures safe operation through sealing an area when required. When the two types have been clearly separated and it is understood that they have different jobs, it becomes much easier to make the right product choice.

In practice, engineering and procurement departments don’t look at the two flanges as they are the same, i.e., they do not substitute a Welding Neck Flange with a Blind Flange or vice versa. Instead, they look at what conditions, maintenance strategy and pipeline purpose is there to meet first and only then decide which flange to ‍‌purchase.