Design security factor

Ignoring the need for design security factors to allow for abnormal situations such as additional air from infiltration. 

If it is then decided to add an air preheater to accomplish heat recovery, the required gross heat input to the furnace will equal required available heat or heat need (%available heat/100) = 13 625 000 h- (48%/10) = 28 400 000 gross Btu/hr. A security factor of at least 25% should be used therefore, the design input should be (28.5 kk Btu/hr) (1.25) = 35.6 gross kk Btu/hr. 

Q13. When designing a flue system, what security factor should be used to make future productivity adjustments possible ... 

A13. A security factor of 1.3 is suggested, applied to the maximum burner firing rate and with flue gas exit temperatures 200°F (111°C) above the furnace running temperature at maximum rates. Some furnace designers may be irritated by these specifications, but they are needed to recover a furnace s normal temperature profile quickly. These specifications are more necessary for a mill with many delays to provide the versatility needed. It is important to be aware of different goals—furnace designers want to build an inexpensive furnace so that they can get the order, but operators want versatility to be able to heat and roll as many tons as possible. 

Coauthor Shannon designed a system considering all the normal deficiencies and with a 20% security factor, but he found that the system was just large enough to control the flue gas temperatiue entering the recuperator. This emphasizes the need to play it safe with expensive long-term equipment design and selection. 

The ideal design is one in which ail parts can be operated satisfactorily with water flowing with the least turbulence and aeration, and at a rate of flow within the limits that the materials involved can securely withstand. These limits, with regard to flow-rate limitations, vary with the material, as described in Section 1.2, but turbulence, aeration or presence of suspended particulates can lower these limits considerably, and designs that eliminate these two factors go a long way towards preventing impingement attack, which can be the major cause of failures in sea-water systems. (See also Sections 1.6 and 2.1.)... 

In the discussion above, conditions described referred to perfect world conditions—that is, to those conditions that we would want (i.e., the security manager s proverbial wish list) to be incorporated into the design and installation of new chemical industry infrastructure. Post-9/11, in a not-so-perfect world, however, many of the peripheral (fence line) measures described above are more difficult to incorporate into chemical industry site infrastructure. This is not to say that industrial chemical facilities do not have fence lines or fences most of them do. These fences are designed to keep vandals, thieves, and trespassers out. The problem is that many of these facilities were constructed several years ago, before urban encroachment literally encircled the sites—allowing, at present, little room for security stand-backs or setbacks to be incorporated into plants or critical equipment locations. Based on personal observation, many of these fences face busy city streets or closely abut structures outside the fence line. The point is that when one sits down to plan a security upgrade, these factors must be taken into account. 

Locks are excellent security features because they have been designed to function in many ways and to work on many different types of assets. Locks can also provide different levels of security depending on how they are designed and implemented. The security provided by a lock is dependent on several factors, including its ability to withstand physical damage (e.g., whether it can be cut off, broken, or otherwise... 

The cartridge case is designed to house the primer, propellant, and to securely retain the bullet in the neck of the case. Cartridge case design is affected by various factors, the most important being ... 

Successful test cases are not just those that are designed to pass but also those that are designed to fail. Good test case design is a key snccess factor in the quality of validation efforts. Of the test cases, above 75% are designed to fail in order to demonstrate the effectiveness of the logical security of the system. 

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