ASME IX QW-402.11 variable
QW-402.11 The addition or deletion of nonmetallic retainers or non-fusing metal retainers. See: Backing vs Retainer in Welding This variable is used so little that makes people have forgotten what it means. It primarily used with the Electroslag welding process. In the case of SMAW process, however, it has the same meaning with backing. Retainers refer to those applications where some non-metallic means is used to keep weld puddle from flowing out of the groove, and in general that it will be in high heat input welding procedure. Remember that the WPS needs not be one piece of paper. During fabrication, … Continue reading ASME IX QW-402.11 variable
ASME IX QW-402.10 variable
QW-402.10 A change in the specified root spacing. Note: The change in the root spacing is frequently addressed by manufactures on separate sheet or by addressing it on fabrication drawing just like joint designs. Root spacing and root gap are used as interchangeable. Do not be confused with these two terms. A root gap from “0 to 50mm (2”)” can be covered by ASME IX, however, a request may be made to have the WPS requalification for the “big” gap if the WPS was not carefully written according to ability of welding technology or welding process to make a sound … Continue reading ASME IX QW-402.10 variable
ASME IX QW-402.4 variable
QW-402.4 The deletion of the backing in single welded groove welds. Double‐welded groove welds are considered welding with backing. Note: From 1980 to 2019, this variable underwent many revisions, to fully understand backing, we need to review the definition of backing in definitions section. Backing: a “material” placed at the root of a weld joint for the purpose of supporting molten weld metal so as to facilitate complete joint penetration. The material may or may not fuse (retainer) into the joint. Backing gas: a gas, such as argon, helium, nitrogen, or reactive gas, which is employed to exclude oxygen from … Continue reading ASME IX QW-402.4 variable
ASME IX QW-402.1 variable
QW-402.1 A change in the type of groove (Vee‐groove, U‐groove, single‐bevel, double‐bevel, etc.). Note: QW-402.1 is frequently addressed by adding a separate drawing of the allowable joint designs permitted by WPS, the actual joint is specified on Fabrication drawing and it should be one of the permitted joint types. In many cases, it is acceptable to permit or specify “Groove and Fillet”, “V-Groove”, “Socket weld and grooves”, ect., in order to satisfy this nonessential variable. Normally, all most nonessential variables leave a lot of judgments up to the manufactures when writing WPS. In some fabrication situations a change in groove … Continue reading ASME IX QW-402.1 variable
ASME IX: WPS variables – Joint design
QW-402.1 A change in the type of groove (Vee‐groove, U‐groove, single‐bevel, double‐bevel, etc.). Please see the interpretation: ASME IX QW-402.1 variable QW-402.4 The deletion of the backing in single welded groove welds. Double‐welded groove welds are considered welding with backing. Please see the interpretation: ASME IX QW-402.4 variable QW-402.5 The addition of a backing or a change in its nominal composition. It is used when the EB insert – fusible backing, incorporated with weldment in GTAW. QW-402.10 A change in the specified root spacing. Please see the interpretation: ASME IX QW-402.10 variable QW-402.11 The addition or deletion of nonmetallic retainers or non-fusing metal … Continue reading ASME IX: WPS variables – Joint design
Pump installation guides
The most important factor in ensuring a pump system offers a long service life is to get the installation right. No amount of good engineering, proper pump selection, or correct application of pumping technology can overcome the challenges a poor installation can throw at a pump system. So it’s critical that we all know the bare minimum requirements to ensure a good installation. Step 1: Read the Manufacturer’s Installation Instructions Virtually all pump manufacturer’s offer Operation and Maintenance Manuals (O&M’s). In addition to information on proper pump operation and maintenance these manuals usually also provide information on how to install … Continue reading Pump installation guides
Pump motor selection
It’s important to size an electric motor properly. Doing so will produce a pumping unit that is more efficient and provides a longer service life. Failing to size the motor correctly will result in a pumping unit that demands more power than it should or one that produces repeated electric faults and may suffer from premature motor failure. A Basic Introduction to Pump Motors Electric motors are generally sized at predetermined intervals. What this means is that in most cases you will need to round up to the next available motor size when determining how large a motor to couple … Continue reading Pump motor selection
Pump Curve Understanding
Years ago, making a pump selection meant sitting down with large printed catalogs and flipping through them until you reached a pump curve that fit a project’s hydraulic requirements. Today this process is made much easier through the use of electronic pump curve catalogs. One of the most well-known developers of electronic pump catalogs is Engineered Software and their pump selection software pump-flo. Another popular option for pump selection software is Intelliquip. All of the curves in this article were generated by Pump-Flo’s web-based pump selection software. What is a Pump Curve? A pump curve is a graphical representation of the performance … Continue reading Pump Curve Understanding
Centrifugal Pump Designs
In a previous article, we discussed some common impeller and casing designs. This article will consider what happens when you put the two together. End-Suction Pumps End-Suction Pump from Wikimedia Commons The most common centrifugal pump design is the end-suction pump. This type of pump combines a volute casing with a variety of impeller designs. Most typically, a radial flow impeller would be used, but in certain specialty applications, Francis-vane or mixed-flow impellers may be used. End-suction pumps are used in a large range of applications. Standard end-suction pumps are commonly used in fire suppression, plumbing, HVAC, and municipal water … Continue reading Centrifugal Pump Designs
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