I am researching gasket installation on FRP piping and vessels and my search results have typically lead back to the vessel/piping or flange manufacturer. I'm curious if there's any empirical data on FG or FRP flanges that details maximum allowable stress? I've also been cautioned in vessel applications that the ability of the flange to accept stresses applied by sealing a joint are often secondary due to the relative strength of the neck coming from the vessel. If anyone has experience with written procedures on gasket installation in FG or FRP applications, it would be most helpful.
I'm not understanding the full problem here I suppose, but I'll venture an answer since no one else has.
With FG and FRP you aren't exactly dealing with high pressure situations. Throw in a full face gasket, make sure you got washers under the nuts, tighten by the usual pattern (i.e. skip around, don't go in a circle), and give it a go.
I would err on the under-tightened side and tighten joints as necessary during a hydrotest to achieve a seal, assuming that cleaning up the water would be less of a pain than replacing a fractured flange.
Is it really absolutely critical that you have a written procedure and achieve a seal on the first try?
- Steve Perry
This post is designed to provide accurate and authoritative information in regard to the subject matter covered. It is offered with the understanding that the author is not engaged in rendering engineering or other professional service. If you need help, get help, and PAY FOR IT.
I'm a little familiar with FRP marine mufflers.
My first choice for termination is a simple nipple, reinforced internally against crushing by a bonded stainless liner, joined to the remainder of the system by a silicone 'hump hose', with triple stainless hose clamps.
My second choice for termination, where flanged joints are required by a class society, are FRP/steel plate swivel flanges, and flanged rubber compensators. The flange bolts are tightened just enough to stop leakage, and silicone or polyurethane sealant is often used on the flange faces to further minimize the torque required.
In both cases, the goal is to minimize the possibility of moment loads from pipe movement being transferred to the (relatively thin) FRP shell through the termination.
Mike Halloran
Pembroke Pines, FL, USA
Thanks for all. further research shows that ASME RTP-1 provides guidelines for material selection and installation. However manufacturers recommendations vary from this. None of the documentation I've found suggests the use of expanded PTFE, which is widely used in the field, although having much higher sealing stresses than the 60-70 durometer elastomers on the RTP-1 spec.
The purpose of this inquiry is/was to develop a series of guidelines for use of expanded PTFE in FRP and fiberglass flange applications. The physical properties and sealing characteristics of the material are well-known. Without some guidance on stress tolerances for FRP or FG flanges, the potential for catastrophic damage to vessels or systems is very real. So is the possibility of litigation resting with the gasket material manufacturer if this kind of failure occurs.
So is the possibility of litigation resting with the gasket material manufacturer if this kind of failure occurs.
Not likely. You'll get the cost of the gasket back, but that's going to be close to the limit of liability from any reputable gasket manufacturer.
Just start easy and tighten only as necessary.
A major FGD OEM uses a combination of split steel backing rings and steel spacers as field remedies whenever they get stuck with with a lap joint or raised face flange mating to an FRP flange. Keep the full face FRP flange from being sprung like a raised face.
Downgrading your bolts might be an option too. Pick one that will yield before you crack a flange. Perhaps A307-B instead of your normal A193s.
- Steve Perry
This post is designed to provide accurate and authoritative information in regard to the subject matter covered. It is offered with the understanding that the author is not engaged in rendering engineering or other professional service. If you need help, get help, and PAY FOR IT.
Further to the astute revelation of Duwe6, in partial explanation flanges have been designed and applied most commonly in the last several decades in general with metallic materials that are much stiffer, less vicoelastic and stronger than the polymers/plastics (that have understandably exhibited relatively more problems).
The goal or guidance 'tightened just enough to stop leakage', though certainly well-meaning, is however in itself neither specific nor measurable, and furthermore may be of questionable practical value in the real world or field environment.
Again thanks to all. Further research shows that ASME RTP-1 is most likely the prevailing document in this area. Two classes of FRP construction are considered. One has a maximum stress value of PSI and the other PSI. Torque recommendations do not exceed 40 ft/lbs. To a gasket material manufacturer these are extremely low figures.
Not only is the low available gasket load an issue with FRP/FG, but bolt stress, both initial and residual are called into question.
Given the limitations set up in RTP-1, gaskets must be highly conformable, and seat under extremely light bolt loads. It should also have excellent recovery characteristics, as residual tension in the fasteners is minimal. For materials other than low durometer elastomers, such as expanded PTFE, this has meant utilizing surface area reduction of the gasket itself to comply with the low load requirements.
90% of all gasket failure is related to things other than material selection. For purposes of making material recommendations, it is imperative to work backward from failure modes to do so. In this case design limitations and field installation practices are the driving forces to develop this recommendation.
I suppose I need to recalibrate my way of thinking...
Assembling low pressure flange joints doesn't even approach a scientific process in my mind. The pipe is already fit, the welds (or equivalent) are already made. I just send a bolting crew (foreman and a few helpers) out to drop in a gasket and tighten the bolts using a standard wrench. Once they claim they're done, I may or may not ping a few bolts before turning the hydro crew loose. If a joint leaks, the bolt crew gets to try again.
High pressure and/or critical joints are another story.
By some of the descriptions indicated here, I wonder if engineers are expecting skilled labor using torque wrenches, tensioners, etc to assemble
every flanged joint to precisely the torque specified by an engineer. Is this really the norm?
- Steve Perry
This post is designed to provide accurate and authoritative information in regard to the subject matter covered. It is offered with the understanding that the author is not engaged in rendering engineering or other professional service. If you need help, get help, and PAY FOR IT.
Torquing is the norm on FRP flanges, at least until the pipefitters develop a "feel" for the correct, very low torque. Any pipefitter with a 12-inch crescent wrench can overtorque and destroy FRP flanges on lines up to 6"NPS. I've seen the aftermath.
I agree that this is not the Design Engineer's problem, and that it belongs to the Field Engineer, the Pipe Supt., and Quality Control. The problem is that our "Leaner, meaner, faster" management eliminated the QC guy, the Pipe Supt. is also filling in for at least one foreman, ahd Mr. Design Engineer is also expected to act as the Field Engineer.
Thus I highly recommend that the required torque values be prominently placed on the drawing(s) the pipefitters will be working to. Mr. Engineer has the resources to easily research the recommended torques. Mr. Pipefitter doesn't, and when he guesses, he guesses too high on FRP flanges.
When working with fiberglass piping systems, it's important to choose the right components, such as FRP flange and GRP flange options, for reliable performance. FRP flanges and GRP flanges are commonly used due to their corrosion resistance and durability. Whether you need an FRP flange and blind or an FRP stub flange, these components are essential for various piping applications. Additionally, FRP pipe flange and fiberglass pipe flange options are designed to provide secure connections in demanding environments. Both fiberglass flange and fiberglass flanges offer similar benefits, ensuring that your piping system remains robust and long-lasting.
Goto Yongchang to know more.
1. Design of GRP/FRP flanges
The existing metal or GRP/FRP molds below DN for FRP flanges are integrally formed with FRP raw materials on the mold by manual layering.
2. FRP Flange Standards
The production, inspection, and acceptance of our company's GRP/FRP flanges are by ASTM "Glass Steel Pipe and Fittings" standards. GRP/FRP flange connection size standards are by ASME B16.5-, ANSI B16.5-, JIS, and other standards, or designed and manufactured by our company according to customer requirements. The existing molds are DN25-DN.
All products can be customized to your needs,so just contact us to learn more details.
3. FRP Flange Parameters
We have different types of flanges, such as bushing, short pipe flanges, and bushing according to different standards.
GRP/FRP flange size table
D(id)
P=0.6Mpa
P=1.0Mpa
P=1.6Mpa
s
L
S
L
S
L
15
12
100
15
100
15
100
20
12
100
15
100
15
100
25(1 inch)
12
100
15
100
18
100
32
15
100
15
100
18
100
40
15
100
18
100
20
100
50(2 inch)
15
100
18
100
22
150
65
15
100
20
150
22
160
80(3 inch)
18
150
20
160
25
230
100(4 inch)
20
150
22
180
28
250
125(5 inch)
22
200
25
230
30
300
150(6 inch)
22
200
28
280
33
370
200(8 inch)
25
220
33
360
38
500
250(10 inch)
28
280
42
420
48
620
300(12 inch)
32
300
48
500
55
350(14 inch)
35
400
54
570
400(16 inch)
40
420
450(18 inch)
45
480
500(20 inch)
50
540
600(24 inch)
52
640
700(28 inch)
55
690
If you have any questions about product parameters, you can contact us at any time!
4. FRP Flange Forming Process
GRP/FRP flange is divided into two integral and bonding flanges according to the forming process
1. Overall flange: The overall flange is generally equal wall thick plate flange. The advantage of this structure is that the flange ring and cylinder are formed together. The reinforced fiberglass and fabric are continuous, giving full play to the characteristics of high FRP strength and ease to form. The broad flange is wholly done entirely by hand-paste.
2. Adhesive flange: The bonding flange is made by processing the flange ring and the flange pipe separately and then bonding the two together. This structure is widely used. It gives full play to the advantages of easy to-form, simple mold, easy to manufacture, suitable for manufacturing large diameter, small-batch, and different types of fiberglass flanges. When the bonding flange is made, feed the pre-processed pipe, make wool at both ends, insert it on the mold seat instead of the core shaft, and process the flange ring.
5. Features and use of GRP/FRP flange parts
1. GRP/FRP flange has excellent physical performance, the specific proportion of GRP/FRP pipe is 1.8-2.1, about 1/4 of steel, of the specific strength is higher than steel, cast steel, and plastic, the weight is generally not more significant than that of the same steel pipe, excellent physical and mechanical performance, in addition, the expansion coefficient of steel, heat conduction coefficient is only 0.5% of steel, is an excellent thermal and electric insulator.
Contact us to discuss your requirements of fiberglass water tank price. Our experienced sales team can help you identify the options that best suit your needs.
2. Chemical corrosion resistance and long service life, suitable for the delivery of various media such as acids, bases, salts, and organic solvents.
3. Excellent hydromechanical characteristics. Hydraulic characteristics are one of the essential characteristics of GRP/FRP pipes. Excellent hydraulic characteristics mean that the fluid pressure head loss is slight, and the transmission pump with a small pipe diameter or small power can be selected to reduce the initial investment of the pipeline engineering, save electric energy and reduce the operation cost. The inner surface of FRP is relatively smooth, and the general surface roughness rate can be 0.008, which can almost be considered as a "hydromechanical smooth pipe." In operation, the inner surface of steel pipe, cast iron pipe, and cement pipe often produces local corrosion and becomes rougher and worse. Fiberglass always maintains the smooth surface of the new pipe.
4. Installation and maintenance cost is low. In general, GRP/FRP pipe does not need special corrosion treatment; the insulation layer can be thinner or even without insulation treatment; light pipe, lifting equipment tonnage, less power consumption, GRP/FRP pipe length is longer than cement pipe and cast-iron pipe, relatively reduced, which will reduce the installation and maintenance cost, which has been proved by many engineering practices at home and abroad.
What is GRP/FRP flange?
FRP stands for "fiberglass reinforced plastic." An FRP flange is a type of flange that is made from fiberglass-reinforced plastic. A flange is a type of connector or coupling that is used to join two pipes or other mechanical components together. It typically consists of a circular ring that is attached to one end of a pipe or component and has an opening on the other end that allows it to be connected to another pipe or component.
FRP flanges are often used in applications where corrosion resistance is important, as fiberglass-reinforced plastic is resistant to many corrosive chemicals. They are also lightweight and easy to install, making them a popular choice in many industries, including chemical processing, water treatment, and oil and gas. However, it is important to note that FRP flanges may not be suitable for all applications, as they may not be as strong or durable as flanges made from other materials, such as metal. It is always a good idea to consult with us to determine the best type of flange for a particular application.
We also provide Phenolic FRP, FRP Grating, FRP Flange Cover, FRP Tee, and FRP Elbow.
40-inch FRP flanges in accordance with ASME B16.47
40-inch FRP flanges in accordance with ASME B16.47