ASME Section VIII, Division 1 is an important engineering standard that provides clear guidelines for creating, inspecting, and certifying pressure vessels. This contributes to standard engineering practices while improving safety and efficiencies across different industries. Post weld heat treatment (PWHT) is a controlled process designed to eliminate residual stresses in welded materials and is defined in clause 331.11 along with tables 331.1.1.1 and 331.1.3. It must comply with requirements set out by clause 331.11.1.2 as set out below for piping applications. Minimum Temperature Post Weld Heat Treatment (PWHT) involves heating weld metal to temperatures below its lower critical transformation temperature and holding for an extended period. This helps reduce residual …

続きを読む “Post Weld Heat Treatment (PWHT) Requirements As Per ASME Section VIII, Division 1”

ASME Section VIII contains comprehensive requirements for the design, fabrication, inspection, testing and certification of fired or unfired pressure vessels with internal or external operating pressures exceeding 15 psig. In addition, this standard provides mandatory and nonmandatory appendices that detail additional design criteria, nondestructive examination standards and acceptance standards that apply. Division 1 As its name implies, Division I of ASME Section VIII code deals specifically with pressure vessels. It specifies the mandatory and nonmandatory construction requirements, along with welding specifications such as WPSs (Welding Procedure Specifications), PQRs, and welder performance qualifications; making certain these documents are correctly documented before placing vessels into service is important. Post-weld heat treatment (PWHT) …

続きを読む “ASME Section VIII Div 2 PWHT Requirements”

PWHT utilizes the Junos operating system and vTrio chip microcode to provide advanced routing, quality of service (HQoS), switching, and security features. The router control plane runs on x86 processors while forwarding is powered by vTrio. Junos OS Release 17.3 provides enhanced aggregated infrastructure for redundant logical tunnel (RLT) interfaces, with anchor and transport logical interfaces being stacked atop an underlaying control logical interface for easier management. Pseudowire Head-End Termination (PWHT) Pseudowire Head-End Termination (PWHT) is an MPLS packet-switched network service that simulates the essential attributes of wire. PWHT connects a Layer 2 circuit from an access node into an L3 service such as L3VPN or EVPN at the provider …

続きを読む “Pseudowire Head-End Termination (PWHT) and PIC Features”

Post weld heat treatment (PWHT) is an essential process used to reduce residual stresses and enhance tensile strength, ductility and toughness in welded metal. Many welding codes mandate PWHT treatments on materials like piping, tanks and pressure vessels for maximum adhesion strength. Preheating involves heating material to specific temperatures for a specified duration, followed by controlled cooling to achieve specific results. A variety of techniques and processes may be utilized. Annealing Annealing is used to relieve internal stresses caused by cold working and other mechanical operations, and to modify metal’s physical properties to increase flexibility and decrease hardness, making them easier to work with. Annealing plays an integral part in …

続きを読む “Post Weld Heat Treatment Methods”

SI was called into assess whether heat had had any detrimental impact on P91 after a fire at a power plant, taking metalurgical replicas for analysis to assess any softening in HAZ regions. Gressler stressed the fact that hardness alone does not determine material health. Instead, an effective screening measure would be monitoring creep strain accumulation using high-temperature strain gauges for creep strain accumulation monitoring as well as engineering analysis to predict its lifetime. Hardness P91 steel family is a 9-12% Cr ferritic/martensitic stainless steel used in nuclear and power plant environments to achieve superior mechanical properties at elevated temperatures. Due to its low carbon, niobium, and nitrogen contents it …

続きを読む “P91 PWHT Chart”

PWHTs are used for many different reasons, including weld preheating, postweld heat treatment, and to address service conditions on carbon steel components. When searching for the ideal machine price, consider factors like: heated parts size, power level, heater and control system (air cooled is often the better choice when heating parts with low heating temperature requirements).

The 2014 edition of ASME B31.3 Code for Process Piping removed PWHT requirements on carbon steel weld materials provided that multi-pass welding techniques and temperatures of at least 95oC (200oF) were employed, as determined through fracture mechanics tests and analyses. These changes reflect fracture mechanics analysis findings. Preheat Temperature Preheat temperature is the keystone to successfully controlling cracking, and must be sufficient to avoid oxidation, delay cooling and provide adequate weld metal toughness. There are various approaches to setting it depending on welding code and section thickness requirements. Welding codes often outline preheat temperature specifications in their welding procedure specifications (WPS) document, so it is crucial that these guidelines are …

続きを読む “ASME B31 3 Eliminated PWHT Requirements”