Gaskets
Spiral Wound Gasket Thickness: 4.5 mm or 3.2 mm?
Gasket thickness is not a free choice; it follows flange size, pressure class and the bolt load…
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Materials
What Is Thermiculite® 835 and Where Is It Used?
It appears often in refinery and petrochemical specifications for critical service: Thermiculite® 835. What is it and which problem does it…
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Gaskets
When Do You Need a Vermiculite Filled Spiral Wound Gasket?
Graphite filled spiral wound gaskets cover most process piping. But once temperature rises and the atmosphere turns oxidising, graphite has a…
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Materials
Vermiculite Versus Thermiculite®
When a specification calls for a "Thermiculite® filled gasket", two questions follow: is this a material or a brand, and will an equivalent be…
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Installation
Calculating Bolt Torque for Spiral Wound Gaskets
"Spiral wound gasket torque chart" is a frequent search. Charts are easy to find, but one that does not state its assumptions is an estimate rather than a…
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Gaskets
Why Gasket Weight Is Asked For on CG and CGI Gaskets
Enquiry lists sometimes carry the note "please include gasket weights". It looks like a detail, but it is needed for air freight, customs declarations and stock…
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Gaskets
Spiral Wound Gasket Colour Code Chart
Two gaskets side by side in the store look identical: one may have a 304 winding, the other 316. That is why the colour code exists. The painted rim tells you the material without…
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Gaskets
How Spiral Wound Gasket Dimensions Are Defined
The size of a spiral wound gasket is not a free choice; the standard and class of the flange it belongs to already define it. State size and class correctly and the rest follows…
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Gaskets
Spiral Wound Gasket Technical Data and Type Selection
We covered construction and colour codes in a separate articlespiral-wound-gaskets-guide.html. This one holds the numbers needed at enquiry and installation: configuration,…
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Gaskets
Spiral Wound Gaskets: Construction, Colour Codes and Installation
The spiral wound gasket is the most widely used metallic gasket in process plants. Selected and installed correctly it seals at high pressure and temperature for its full service…
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Procurement
What Is an Approved Manufacturer List (AML)?
Large projects add a line to the specification: only manufacturers on the approved manufacturer list are acceptable. It is a condition that directly affects both quotation and…
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Flanges
What Is a Studding Outlet (Pad Flange)?
A studding outlet is a flange shaped connection welded to a vessel or pipe surface on one side and drilled with tapped holes on the other. Unlike a standard flange the holes do…
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Field
Flange Flatness and Runout Tolerance
A flanged joint seals because two faces meet parallel to each other. If one face is tilted, the gasket is crushed too much on one side and too little on the…
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Materials
Nickel Alloy Flanges: Inconel, Monel and Hastelloy
Where stainless and duplex grades fall short, nickel based alloys take over. They are expensive materials, used where genuinely needed rather than chosen "to be…
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Materials
How to Read ASTM Material Codes
Most of the confusion on enquiry lists comes from material codes. Once the logic is clear, it takes one glance to know what an item…
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Manufacturing
How Flanges Are Manufactured: From Billet to Delivery
A flange's quality is decided at every step of the chain, not at final inspection. Knowing the process makes it easier to ask the right questions at enquiry and…
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Maintenance
The Main Causes of Flange Leaks
A leak is usually explained as "a bad gasket". The gasket is normally the consequence; the real cause sits one step…
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Maintenance
Flange Face Protection: Why Covers Matter
If a flange arrives on site with a scratched face, it is either remachined or it becomes the joint that leaks at the next shutdown. Protection starts before…
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Materials
Stainless or Carbon Steel? Cost Against Service Life
On most projects this decision is made on first cost. Yet the difference between carbon steel and stainless has far more to do with service life and maintenance than with the…
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Maintenance
What to Do With a Damaged Flange Face
Finding scratches, dents or corrosion pits on a flange face during maintenance is common. The decision lies between three options: close it as it is, repair it, or replace…
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Flanges
Where Are Long Weld Neck (LWN) Flanges Used?
A long weld neck flange is a weld neck flange with an extended hub. That extension turns the part from a flange into a short nozzle…
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Materials
High Yield Flanges: The A694 Grades
Pipeline projects ask for A694 F52 or F65 rather than A105. The reason is simple: the flange has to match the strength of the pipe it…
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Flanges
ANSI or ASME? Getting the Standard Name Right
In the field people say "ANSI flange" and "ASME flange" interchangeably. Both point to the same part, but the organisations differ, and the confusion occasionally causes ordering…
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Flanges
The Difference Between JIS and ANSI Flanges
In plants with Japanese pumps, compressors or heat exchangers the equipment side is often JIS flanged. If the piping was designed to ASME, the connection point becomes a…
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Flanges
Threaded or Socket Weld? Small Bore Connection Choice
Small bore lines offer two options: a threaded connection or a socket weld. The choice depends on service and vibration, not only on…
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Flanges
The Difference Between Class 150 and Class 300 Flanges
This is the comparison made most often when choosing a flange class. Both exist in the same nominal sizes, yet they are not…
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Flanges
Nipoflange, Weldoflange and Flangeolet Compared
Taking a flanged branch from a main run classically needs three parts: an olet welded to the run, a nipple on top and a flange at the end. Three parts, three welds. Combined…
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Flanges
Selecting Flanges for High Pressure and High Temperature
High pressure and high temperature are demanding on their own; together they force every part of a flanged joint to be…
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Flanges
DIN/EN Versus ANSI/ASME Flanges
This is the mismatch met most often on international projects: metric DIN/EN flanges on one side, imperial ANSI/ASME flanges on the…
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Procurement
Five Common Mistakes When Ordering Flanges
A wrong flange costs far more than the material: the line waits, the crew stands idle and the schedule slips. These five mistakes are the ones we see most often on enquiry…
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Materials
Forged or Cast? The Difference in Flanges and Valve Bodies
"Would a cast one do?" comes up from time to time on flange orders. The answer depends on the item and where it will…
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Materials
Offshore Versus Onshore Flanges
Even carrying the same fluid, a line on an offshore platform is not solved with the same material as one onshore. The difference comes from the environment and the logistics…
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Flanges
How to Calculate Blind Flange Thickness
For standard sizes, blind flange thickness is read from the table and no calculation is needed. Calculation comes in for non standard sizes, custom blanking plates and blinding…
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Installation
How to Determine Stud Bolt Dimensions
In the field an "about right" dimension means either a leaking joint or a stripped nut. Three dimensions must be given together when ordering studs: diameter, thread and…
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Certification
When Is PMI Testing Needed?
PMI measures the alloy composition of a part with a portable spectrometer. The result comes in seconds and shows whether the material really is the grade…
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Certification
PED, ASME, API and ISO: What Each One Covers
"Which standard is stricter?" comes up often, but there is no direct answer, because these standards approach the same subject from different…
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Field
NPT Versus BSPT Threads
Two thread systems dominate threaded connections: American NPT and British BSPT. From a distance both look like tapered threads, but they do not fit…
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Maintenance
Galling, Handling and Surface Contamination in Stainless
Stainless steel is durable, but handled carelessly it creates unexpected problems. The two seen most often in the field are galled fasteners and faces contaminated with carbon…
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Flanges
How to Read a Flange Dimension Table
A flange dimension table is not complicated, but the columns and footnotes confuse anyone seeing one for the first time. Once a few basics land, the table reads…
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Materials
ASTM A105 or A182? Comparing Flange Materials
This is the question we hear most often when a flange is ordered: A105 or A182? They are not two materials but two standard…
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Flanges
Above 24 Inches: ASME B16.47 and MSS SP-44
ASME B16.5 covers flanges up to 24 inches. Above that, ASME B16.47 takes over, and it contains two different…
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Materials
Selecting Flanges for Hydrogen Service
Hydrogen lines create two separate problems: the molecule is so small that it escapes easily, and hydrogen atoms enter the steel and make it…
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Materials
Brittle Fracture in Cold Service and A350 LF2
At room temperature carbon steel behaves in a ductile way: it stretches before it breaks. As temperature falls that behaviour changes, and below a certain point the material…
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Flanges
Flange Face Finish: Why the Ra Value Matters
Face type and surface finish are two different specifications. One describes the form RF, FF, RTJ, the other the machining pattern on that form. The gasket seals by keying into…
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Materials
NACE MR0175: Material Selection for Sour Service
Once a specification says "sour service", the subject is no longer only pressure and temperature. Hydrogen sulphide changes how steel behaves, and a material that is otherwise…
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Flanges
Reducing Flanges: When Do You Need One?
When two different pipe sizes have to meet at a flanged joint there are two routes: weld in a reducer and use a normal flange, or use a single piece reducing flange. Which is…
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Flanges
RTJ Flanges: What They Are and When to Use Them
Above class 300, particularly in upstream oil and gas and refining, the face type is often specified as RTJ. Sealing here comes not from crushing a gasket but from permanent…
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Maintenance
Spectacle Blinds, Figure 8 Blanks and Line Blinds
Every refinery and process plant has a drawer full of steel parts that look like giant spectacles. They are the blinding elements that prove a line is truly isolated during…
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Flanges
What Is an Orifice Flange and Where Is It Used?
The most common way to measure flow in a pressurised line is to restrict the flow and measure the pressure difference it creates. An orifice flange set is the connection that…
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Certification
How to Read a Mill Test Report (MTR)
The most important document in a shipping file is the material certificate. It is usually filed and forgotten, yet checking a few lines prevents problems in the…
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Field
How to Read Flange Markings
The marks on the rim of a flange are not random. The standard defines what has to be stamped, and reading those lines tells you almost everything about the…
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Installation
Flange Bolt Torque and Tightening Sequence
Even with the right flange, the right gasket and the right bolts, a joint leaks if the torque is wrong. Torque delivers the force that compresses the gasket enough to seal without…
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Flanges
When and Why Use a Flanged Connection?
The tightest way to join a line is to weld it. Even so, plants contain thousands of flanged joints, for a simple reason: a welded line cannot be taken apart, a flanged one…
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Materials
Stainless Flange Selection: 304 or 316?
The sentence we hear most often when a stainless flange is requested is "304 will do, it is stainless anyway". But stainless steel does not resist corrosion absolutely; it resists…
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Maintenance
How to Prevent Corrosion on Flanges
In a planned outage the biggest time loss is often not the flange itself but bolts that will not come off. Corrosion damages the sealing face and multiplies maintenance…
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Flanges
Weld Neck or Slip-On Flange: Which One?
When two flange types of the same size and class are compared, the decision is usually made on price. Yet the difference between weld neck and slip-on has far more to do with the…
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Field
Five Rules for Fitting a Flange for the First Time
A flanged joint looks simple: two parts, a gasket and a few bolts. Most field leaks start from exactly that assumption. The five rules below cover the mistakes made most often on…
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Flanges
What Is a Blind Flange and Where Is It Used?
The safest way to close a pipeline is not to weld a cap on it, but to leave a removable cover. That is exactly what a blind flange does: it holds the line under pressure yet can…
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Materials
What Is an ASTM A105 Flange and What Are Its Limits?
ASTM A105 is the first material that comes to mind for a carbon steel flange. It is the most widely used forged grade on process lines, but it is not suitable for every service.…
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Field
How to Identify an Unmarked Flange in the Field
When a flange with unreadable markings turns up in the store or on a dismantled line, there are two options: guess, or measure. Guessing means a part of the wrong pressure class…
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Gaskets
How to Select a Flange Gasket
The gasket is the cheapest part of a flanged joint, yet most leaks start there. The choice comes down to four pieces of information: pressure, temperature, fluid and flange…
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Flanges
Flange Face Types: RF, FF and RTJ Explained
The flange face is where the gasket sits and where sealing actually happens. Two flanges of the same class and size are not a safe joint if their face types…
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Flanges
Flange Types: Which One for Which Job?
ASME B16.5 defines six main flange types. They all appear to do the same job: joining two parts so they can be taken apart again. What differs is how they carry load and where the…
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Materials
When Do You Need a Duplex Stainless Flange?
316L is not enough in every environment. When chloride and temperature rise together, austenitic grades become open to stress corrosion cracking. That is where duplex grades come…
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