Joints processing conditions

The EDC cracking processes that are being licensed most successfully are the joint process of Goodrich and Farbewerke Hoechst and those of Stauffer, Toyo Soda, and Kureha. These processes are generally similar, but the operating conditions can vary widely. Most plants use separate feed streams of acetylene and ethylene, but in some the feed streams are mixed. Union Carbide, Kureha, and Japanese Geon all have processes that produce VCM from mixed acetylene-ethylene feed stocks. 

When selecting a bellows valve, it is important to pay some special attention that the material selection is in accordance with the process conditions. Some SRV manufacturers use as standard bellow material INCONEL alloy 625LCF-UNS N06625 (ASME SB0443). This material is not perfect either but, compared to simple stainless steel, has an enhanced resistance to mechanical fatigue and sour gases it is commonly used in refinery FCC systems for expansion joints. 

The physical and chemical nature of the metal substrate surface depends on the bulk alloy composition, processing conditions used, and any preconditioning environments that the substrate may be exposed to during fabrication and storage. Once the joint is assembled, the physical and chemical nature of the adhesive-metal interface may change due to the environment and to the chemical nature of the adhesive. 

UOP and Norsk Hydro have jointly developed and demonstrated a new MTO process utilizing a SAPO-34 containing catalyst that provides up to 80% yield of ethylene and propylene at near-complete methanol conversion. Some of the key aspects of the work have included the selection of reactor design for the MTO process and determination of the effects of process conditions on product yield. Evaluation of the suitability of the MTO light olefin product as an olefin polymerization feedstock and demonstration of the stability of the MTO-lOO catalyst have also been determined during the development of this process. 

They previously developed a consortium (i.e., a mixture) of microorganisms that could be immobilized in biological reactors and that was subsequently used to define process conditions for the treatment of an HE-contaminated waste stream. In this feasibility study performed jointly by LLNL and UCLA, experiments were conducted to define the tolerance of this denitrifying consortium to salinity and dilutions of base hydrolysate. 

Two additional defects are seen in FSW of lap joints (Fig. 13.26). Under hot processing conditions, the zone V flow observed in the... 

One-part epoxy adhesives include solvent-free liquid resins, solutions in solvent, liquid resin pastes, fusible powders, sticks, pellets and paste, supported and unsupported films, and preformed shapes to fit a particular joint. Two-part epoxy adhesives are usually comprised of the resin and the curing agent, which are mixed just prior to use. The components may be liquids, putties, or liquid and hardener powder. They may also contain plasticizers, reactive diluents, fillers, and resinous modifiers. The processing conditions are determined by the curing agent employed. In general, two-part systems are mixed, applied within the recommended pot life (a few minutes to several hours), and cured at room temperature for up to 24 hours, or at elevated temperatures to reduce the cure time. Typical cure conditions range from 3 hours at 60°C to 20 minutes at 100 C. ... 

Minford also studied the effects of four different phosphoric acid processing conditions under stress and intermittent salt-water immersion testing of 6061-T6 aluminum alloys. None of the joints pretreated by varying phosphoric acid anodizing conditions failed after 480 days exposure, even... 

A major food, deteigent, and consumer products compaiy had defined some piping expansion problems. The solution seemed obvious and several flexible elastomer expansion joints were selected and installed to meet the process conditions within a soap... 

While in the standard optimization approach for batch processes, one has as constraint the (possibly ill-conditioned) open-loop full process dynamics, in the proposed approach one has as constraint the reduced order (well-conditioned) inverse dynamics in conjunction with a fast linear filter. In other words, the proposed constructive procedure constitutes a means to simplify and robustify the search of the optimal solution for the joint process and control problem. 

Several of the joining process conditions and produced material phases in joint for SiC composites were summarized by Katoh, as shown in Table 12.7. 

The quality control of adhesively bonded joints in fabrication lines includes control of adhesion processes, appropriate design of joints to ease the process control, and education and direction for works to conduct the manufacturing. Many efforts have been made to improve the quality stabilities (Petrie 2007 Espie 1995 Roberts 1990 DeFrayne 1983 Bandaruk 1962). Due to the invention of new types of adhesives such as acrylics whose strengths are less sensitive to processing conditions than those of conventional adhesives, the quahty control can he done more easily and precisely in these days than the previous as shown by Haraga et al (2009). 

As mentioned in the introduction, adhesives are process materials. This is similar to a welding process. For these processes, it is very difficult to control the quality of a bonded joint in a nondestructive way. Therefore, it is crucial to control the process parameters of each production step, to check the properties of the adhesive with the real substrates and it is necessary to control the surface conditions of the substrates itself. And even with nondestructive testing methods it is not possible to check the quality and durability of the adhesion itself This can only be done with thorough adhesion tests upfront with original substrates and original process conditions. 

It is true the repair of bonded joints is different from that of bolt-on parts. But in comparison with riveted, spot welded, or welded structures, the removal of bonded parts may be even easier. When repairing bonded metal structures, the removal of a damaged part is done by mechanical abrasion or with hammer and chisel. The adhesive is then removed by abrasion like it is done with painted surfaces. More challenging in the repair case is to bond a new part on the old structure. It is not possible to use the same adhesive as in the production line since the process conditions are different. In this case, 2-C high strength adhesives with improved impact resistance can be used as published by Lutz (2009). And to process these adhesives correctly, well-educated personnel is required. 

---