American Petroleum Institute

Safe Operation of Hydrofluoric Acid Alkylation Units - Second Edition
 N RP 751

Annotation

FOREWORD

In January 1990, API issued Recommended Practice 750, Management of Process Hazards, which outlines the key elements of a comprehensive program for managing all potentially hazardous processes. In April 1991, API issued a background paper entitled "The Use of Hydrofluoric Acid in the Petroleum Refining Alkylation Process." [1] The paper outlines four systems that, if properly installed and maintained, will minimize the risks associated with this process. Although these documents will have a beneficial impact on hydrofluoric acid (HF) alkylation safety, a supplemental document that expands on concerns specific to HF alkylation can have an even larger effect. This recommended practice, developed by an API committee concerned with further improving the industry's good safety record, is intended to serve that purpose. It is an outline of many of the practices used effectively in the industry to minimize the process hazards of HF alkylation. Throughout this recommended practice, it is assumed that the reader is familiar with API Recommended Practice 750.

HF alkylation is a widely used refinery process important in producing a significant share of the nation's high-quality motor gasoline. The acid used in these units is a hazardous and corrosive liquid which, if accidentally released, can form a vapor cloud. Contact with HF liquid or vapor can result in serious, painful chemical burns and adverse health effects, sometimes with delayed onset.

However, with proper design of alkylation units and careful process management, the acid in these units does not present a significant risk to the community or the environment. This process has been operated for over 50 years, with only a small number of incidents affecting the surrounding communities. Moreover, improvements in process design and management are continually being made to further reduce the risks to workers and surrounding communities. The petroleum and chemical industries have conducted extensive research on HF alkylation safety; the results are being used to prevent incidents and to mitigate the effects of an incident if one occurs.