Risk Reduction; Residual Risk; Machine Safety In The Usa; Minimum Requirements Of The Osha - Siemens SINUMERIK 808D Function Manual

Risks must be reduced by designing and implementing the machine accordingly (e.g. by means of controllers or protective
measures suitable for the safety-related functions).
If the protective measures involve the use of interlocking or control functions, these must be designed according to EN ISO
13849-1. For electrical and electronic controllers, EN 62061 can be used as an alternative to EN ISO 13849-1. Electronic
controllers and bus systems must also comply with IEC/EN 61508.
22.1.2.8

Risk reduction

Risk reduction measures for a machine can be implemented by means of safety-related control functions in addition to
structural measures. To implement these control functions, special requirements must be taken into account, graded
according to the magnitude of the risk. These are described in EN ISO 13849-1 or, in the case of electrical controllers
(particularly programmable electronics), in EN 61508 or EN 62061. The requirements regarding safety-related controller
components are graded according to the magnitude of the risk and the level to which the risk needs to be reduced.
EN ISO 13849-1 defines a risk flow chart that instead of categories results in hierarchically graduated Performance Levels
(PL).
IEC/EN 62061 uses "Safety Integrity Level" (SIL) for classification purposes. This is a quantified measure of the safety-
related performance of a controller. The required SIL is also determined in accordance with the risk assessment principle
according to ISO 12100 (EN 1050). Annex A of the standard describes a method for determining the required Safety
Integrity Level (SIL).
Regardless of which standard is applied, steps must be taken to ensure that all the machine controller components required
for executing the safety-related functions fulfill these requirements.
22.1.2.9

Residual risk

In today's technologically advanced world, the concept of safety is relative. The ability to ensure safety to the extent that risk
is ruled out in all circumstances – "zero-risk guarantee" – is practically impossible. The residual risk is the risk that remains
once all the relevant protective measures have been implemented in accordance with the latest state of the art.
Residual risks must be clearly referred to in the machine/plant documentation (user information according to EN ISO 12100-
2).
22.1.3

Machine safety in the USA

A key difference between the USA and Europe in the legal requirements regarding safety at work is that, in the USA, no
legislation exists regarding machinery safety that is applicable in all of the states and that defines the responsibility of the
manufacturer/supplier. A general requirement exists stating that employers must ensure a safe workplace.
22.1.3.1

Minimum requirements of the OSHA

The Occupational Safety and Health Act (OSHA) from 1970 regulates the requirement that employers must offer a safe
place of work. The core requirements of OSHA are specified in Section 5 "Duties".
The requirements of the OSH Act are managed by the "Occupational Safety and Health Administration" (also known as
OSHA). OSHA employs regional inspectors who check whether or not workplaces comply with the applicable regulations.
The OSHA regulations are described in OSHA 29 CFR 1910.xxx ("OSHA Regulations (29 CFR) PART 1910 Occupational
Safety and Health"). (CFR: Code of Federal Regulations.)
http://www.osha.gov
The application of standards is regulated in 29 CFR 1910.5 "Applicability of standards". The concept is similar to that used in
Europe. Product-specific standards have priority over general standards insofar as they cover the relevant aspects. Once
the standards are fulfilled, employers can assume that they have fulfilled the core requirements of the OSH Act with respect
to the aspects covered by the standards.
In conjunction with certain applications, OSHA requires that all electrical equipment and devices that are used to protect
workers be authorized by an OSHA-certified, "Nationally Recognized Testing Laboratory" (NRTL) for the specific application.
In addition to the OSHA regulations, the current standards defined by organizations such as NFPA and ANSI must be
carefully observed and the extensive product liability legislation that exists in the US taken into account. Due to the product
liability legislation, it is in the interests of manufacturing and operating companies that they carefully maintain the applicable
regulations and are "forced" to fulfill the requirement to use state-of-the-art technology.
Third-party insurance companies generally demand that their customers fulfill the applicable standards of the standards
organizations. Self-insured companies are not initially subject to this requirement but, in the event of an accident, they must
provide verification that they have applied generally-recognized safety principles.
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