ASME STP-PT-085 pdf free download

ASME STP-PT-085 pdf free download EFFECT OF HOT WIRE FILLER METAL ADDITION ON GTAW HEAT INPUT FOR CORROSION RESISTANT OVERLAYS
1BACKGROUND AND INTRODUCTION
Steel piping, valves, blow-out preventers (BOPs), and other processing components require protection fromcontact with hydrogen sulfide-laden oil or gas. These “sour” products are the current norm for deep wellsin the Gulf of Mexico and other areas.Corrosion-resistant alloy overlays are also used in the pressure vesselindustry for various applications. Without a protective layer of a corrosion-resistant alloy,catastrophicfailures,due to stress-corrosion cracking,will occur. The prominent method for application of thisprotective layer is to apply a CRO using some welding process.The process most favored is the gas tungstenarc welding process using an energized filler metal feed, commonly referred to as “hot wire”(GTAW-HW).By preheating the filler wire, greater deposition rates can be achieved.
ASME BPVC Section IX does not address the use of hot wire filler metal addition in terms of parameterlimits or whether the power is included in the determination of heat input rate(HIR)’. In upstream(pre-refinery) oil and gas applications, the tendency has been to add this secondary (hot wire) power to theprimary (arc) power to calculate HlR; however, there have been questions raised in terms of whether thesecondary power actually contributes to the amount of energy being supplied to the base metal or isconsumed in the process of preheating the filler metal.This study will attempt to quantify what contribution,if any, is provided by the secondary power to affect the resulting HAZ. properties and chemical compositionof the CRO.
1.1Project Objective
The primary objective of this study was to determine if any technical justification exists for considerationof the addition or modification of essential variables to include the secondary power from hot wireadditions.
1.2Materials
While this topic may be of interest in other industries and applications, it is known to be of concern in theseupstream oil and gas applications. ARC Specialties is the leading producer of automated welding systemsused for applying CROs to a variety components, with 300+ systems in operation around the world. Whileseveral different welding processes are employed in these systems, the vast majority utilize GTAW-HW.Consequently，the materials chosen for this study will be those most commonly employed for theseupstream oil and gas applications. The two base metals most commonly employed are quenched andtempered versions of AISI4130 and 2’/4 Cr- 1 Mo(P-5A, Grade 22). In most cases, the forged versions ofthese base metals are used; however, this adds significantly to the cost. In the original proposal, Grade 22was the only material to be included in this study, but there is far more 4130 material used than Grade 22.Consequently, to provide more data, pipe grades of the two materials were used because compositionallythe pipe and forging materials are virtually identical. Below are the two base metals to be used for thisstudy, and material certs are attached:
. SA335 Grade P22 – Ht #986957- CEw = 0.825;8.625 inches OD x 0.812 inches wall.A519 Grade 4130 – Ht #J4038- CEw = 0.663;8.625 inches OD x 1.5 inches wall
The overlay material was InconelR625(SFA5.9，ERNiCrMo-3). The size used was 0.045 inches(1.2 millimeter (mm)) diameter. Lincoln offered to supply the filler metal for this work. The type andclassification are shown below and the material cert is attached.
· 0.045 inches [ 1.2 mm] TECHALLOY 62533SSP- Ht #QT594
2 WELD TRIAL MATRIX – CRO WELDS
Two series of CROs were welded on each base metal for a total of four series. One series for each base metal was welded using conventional parameters where the weld metal deposition rate is approximately 2 pounds per hour. The second series for each base metal was welded using newly developed parameters which result in higher deposition rates on the order of 8 pounds per hour. The parameters used for the higher deposition rates actually result in lower heat input rates, so this provided even more test data.
Welding was conducted on pipe coupons using ARC’s next generation HVT system. The welding system is capable of welding in a variety of welding positions by rotating the frame holding the turntable and welding torch. The frame can be rotated from 0-90 degrees. Images of the welding system in the two configurations are shown below in Figure 2-1 and Figure 2-2. All of the samples for this study were welded in the flat (1G) position as shown in Figure 2-2. While the plan was to run the samples at pre-established settings, there is a need to make minor adjustments.
The primary 2 amperage, wire feed speed and travel speed can be preset accurately; however, there is a need to make minor adjustments to the secondary 3 amperage, primary voltage and secondary voltage to stabilize operation and assure good wetting. Every attempt was made to adjust the filler wire guide tube consistently with respect to the end of the tungsten electrode, however, minor secondary amperage and voltage adjustments are inevitable. Similarly, the entry point of the filler wire was held constant, as much as practicable. For all of these test welds, the filler wire was introduced at the rear of the molten pool, which is typical for hot wire feed, but different from typical cold wire operation, where the wire is most often introduced at the leading edge of the weld pool.