Hot tapping

Advantages of the pitot method of measurement are low pressure loss and easy installation. In some cases, installations in existing lines are made without process shutdown by hot tapping the line (7). 

API Publ 2201, Procedures for Welding or Hot Tapping on Equipment in Service, 4th ed., September 1995. 

The installed eost is primarily determined by the size of the unit. However, other faetors may have a signifieant impaet on this eost. The eonneetion to the gas system eould be expensive if speeial hot tap fittings are required. If sound attenuation is neeessary for the ehosen loeation, this ean also have an impaet on the overall eost. The eonneetion to the eleetrieal system ean add signifieant eost if distanees are far or high-voltage switehgear is neeessary. Equipment manufaeturers are able to provide eost estimates for major equipment. The installation eosts are site speeifie and require individual studies and estimates. 

There was a leak on the line supplj ing steam to a plant. To avoid a shutdown, a hot tap and stopple was carried out, that is, the line was bypassed and the leaking section plugged off (stoppled) while in use. The job went well mechanically, but the leak continued. It was then found that the leak was not coming from the steam line but from a hot condensate line next to it. The condensate flashed as it leaked, and the leak looked like a steam leak [26],... 

Without consulting the manufacturer, the owner of a set of hot tapping equipment made a small modification he installed a larger vent valve to speed up its use. As a result the equipment could no longer withstand the pressure and was violently ejected from a pipeline operating at a gauge pressure of 40 bar (600 psi) [22]. 

Preparation of Emulsions. The entire aqueous phase was stirred until all solids were dissolved. Sufficient water was withheld from the formulation so small volumes of experimental and control components could be added to emulsion subsamples. Sulfuric acid (1 N) was added to the aqueous phase to decrease the pH to 5.7. The two phases in separate containers were blanketed with nitrogen, sealed, and heated to 75 in an 80 water bath (about 30 minutes). The hot oil phase was stirred slowly and blanketed with nitrogen, then the hot aqueous phase was quickly added while stirring. The emulsion was blanketed with nitrogen and slowly stirred (about 2 hours) in the stoppered container until ambient temperature ( 25 ) was reached. Subsamples of the master batch were removed for the addition of experimental components and stored in 1-oz containers. The containers had been washed with hot tap water, deionized water, and methanol, then dried at 120 . 

Mechanical fittings may be used for making hot taps on pipelines and mains, provided they are designed for the operating pressure and temperature of the pipeline or main. 

A hot tap shall not be considered a routine procedure, but shall be used only when there is no practical alternative. A hot-tap thermal analysis program shall be used to review, analyze, and provide the product flow and weld parameters during the hot tap. Examples of conditions where hot tapping is not permitted are as follows ... 

The special Jet Tapper Blasting Caps have been designed to withstand prolonged exposure to high temperatures. Experience has shown that they will stay in a hot tap hole for from three to eight minutes before detonating when they are used as part of the Jet Tapper assembly... 

Omnion recommends that polycarbonate conductivity tubes, conductivity probes, glass aeration tubes, and silicone tubing be soaked in very hot soapy tap water (1% detergent) for 1 hr, rinsed in hot tap water, soaked in hot tap water for an additional 1 hr, and finally rinsed with distilled water and allowed to soak in distilled water until used. 

Scrupulously cleaned glassware is essential. Glassware that has previously been used for alditol acetates should first be washed in dichlo-romethane (DCM) to remove any traces of alditol acetates. Tubes should then be washed using high-quality detergent, rinsed at least 6 times in hot tap water, and then at least two times in distilled water, and allowed to dry. 

The sections are rinsed in TBS, and then exposed to DAB+ chromogen (Dako) for a few minutes as the substrate for the EnVision-HRP-enzyme. The sections are washed by shaking the slide rapidly under tap water for 10 sec. The excess fluid is removed from the slide with a paper towel. The slide is dipped in distilled water, counterstained with Meyer s hematoxylin for 15 sec, and then rinsed in hot tap water at 42°C for 30 sec. 

Put one cup of hot tap water in the two-cup measuring cup. Add one-half cup of sugar to the hot water. Stir the water with a spoon until the sugar dissolves. You can no longer see the sugar when it dissolves. 

Henri de Pitot invented the Pitot tube in 1732. It is a small, open-ended tube that is inserted into the process pipe with its open end facing into the flow. The differential between the total pressure on this open impact port and the static pipeline pressure is measured as an indication of the flow. The Pitot tubes provide a low-cost measurement with negligible pressure loss and can also be inserted into the process pipes while the system is under pressure (wet- or hot-tapping). They are also used for temporary measurements and for the determination of velocity profiles by traversing pipes and ducts. 

Good communications are critical. If there are special situations, such as hot tapping, or unique conditions in which hazardous materials cannot be easily removed (such as the accumulation of solids that cannot be dissolved away), or if the clearing procedures cannot be followed or do not exist, then key professional personnel must perform a hazards analysis and re-evaluate the situation. Personnel must not continue scheduled maintenance until safety can be guaranteed. [30]... 

Unique one-time specialty maintenance such as chemical cleaning, hot tapping, freezing water in pipelines to work downstream of the ice plug. 

Maintenance Considerations Equipment Inspection Premodification Periodically in Service Trip and Alarm Testing Maintenance Procedures Specialty Contractors Line Freezing Hot Tapping or Stopple On-Stream leak repair... 

When the gel is prepared using stock solutions stored at 4°C the mixture should be warmed to room temperature by swirling under the hot tap to prevent irregular polymerization around the slot former. Add 40 /d TEMED and 300 ju.1 of 10% ammonium persulphate to 50 ml of gel solution and mix by swirling. 

The silica surfaces used were fused silica microscope slides (1 X 2 X 1/16 inches, A. H. Thomas and Co.) and the alumina surfaces were 3/4 inch diameter, 1/8 inch thick, synthetic, a-alumina discs (synthetic sapphire, Linde Division, Union Carbide Corp.). The specimens were cleaned by heating in a mixture of equal parts of sulfuric and nitric acid, given a preliminary rinse in hot tap water and then soaked in three suc-... 

Using redox potentials, explain the frequent occurrence of perforations in domestic hot tap water pipes manufactured from galvanized steel. 

If some of the Bis-GMA sticks to the sides or top of the vial, tightly screw on the vial lid and completely submerge the vial in a beaker full of hot tap water until the Bis-GMA flows to the bottom. 

A distinction should be made between the bubbles which are formed by cavitation and those which occur naturally in the parent liquid or are induced by ultrasonic action (sparging). Cavitation bubbles, which range in size from infinitesimal to visible (40 pm and above) appear only when the radiating surface is activated and vanish apparently instantaneously when the power is turned off (in fact, they vanish within a half-cycle or 25 X 10 s at 20 kHz). Naturally occurring bubbles of entrapped air or other gases are most evident in freshly poured hot tap water as cloudiness or in still water as small bubbles adhering to the undersurface and the vessel walls. Sparged bubbles, which are those induced mechanically by external means such as ultrasonic action at or near the gas-liquid interface (the surface), tend to float in the liquid and even produce foam. 

Dip a cloth washcloth in hot tap water, being careful to test the heat against your wrist to prevent a burn. 

BNHS ester 34 mg/mL of dimethylformamide in a glass test tube, dissolved by heating briefly in hot tap water (60°C). 

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